What contributes to the greenhouse effect at lower atmospheric levels, but in the upper atmosphere protects life on Earth?

Climate Change: Vital Signs of the Planet: Causes Vital Signs of the Planet Questions (FAQ) A blanket around the Earth A layer of greenhouse gases – primarily water vapor, and including much smaller amounts of carbon dioxide, methane and nitrous oxide – acts as a thermal blanket for the Earth, absorbing heat and warming the surface to a life-supporting average of 59 degrees Fahrenheit (15 degrees Celsius). Most climate scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect" 1 — warming that results when the atmosphere traps heat radiating from Earth toward space. Certain gases in the atmosphere block heat from escaping. Long-lived gases that remain semi-permanently in the atmosphere and do not respond physically or chemically to changes in temperature are described as "forcing" climate change. Gases, such as water vapor, which respond physically or chemically to changes in temperature are seen as "feedbacks." Gases that contribute to the greenhouse effect include: Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect. Carbon dioxide (CO2). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Humans have increased atmospheric CO2 concentration by more than a third since the Industrial Revolution began. This is the most important long-lived "forcing" of climate change. Methane. A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. On a molecule-for-molecule basis, methane is a far more active greenhouse gas than carbon dioxide, but also one which is much less abundant in the atmosphere. Nitrous oxide. A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning. Chlorofluorocarbons (CFCs). Synthetic compounds entirely of industrial origin used in a number of applications, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. They are also greenhouse gases. Not enough greenhouse effect: The planet Mars has a very thin atmosphere, nearly all carbon dioxide.  Because of the low atmospheric pressure, and with little to no methane or water vapor to reinforce the weak greenhouse effect, Mars has a largely frozen surface that shows no evidence of life. Too much greenhouse effect: The atmosphere of Venus, like Mars, is nearly all carbon dioxide. But Venus has about 300 times as much carbon dioxide in its atmosphere as Earth and Mars do, producing a runaway greenhouse effect and a surface temperature hot enough to melt lead. On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases. The consequences of changing the natural atmospheric greenhouse are difficult to predict, but certain effects seem likely: On average, Earth will become warmer. Some regions may welcome warmer temperatures, but others may not. Warmer conditions will probably lead to more evaporation and precipitation overall, but individual regio


What is the name of the process by which substances are washed out of the soil?

Ch02 Some countries poison soils Why should the leaders of countries today commit their governments and their people to the hard work and expense of a national programme of soil conservation? The answer is that soil takes many years to create, but it can be destroyed in almost no time at all. With the loss of soil goes man's ability to grow food crops and graze animals, to produce fibre and forests. It is not enough to describe the soil as a country's greatest source of wealth; it is more than that; it is a country's life. And in one country after another today, the soil is washing or blowing away.   Soil is a complex mixture Soil covers most of the land surface of the earth in a thin layer, ranging from a few centimetres to several metres deep. It is composed of rock and mineral particles of many sizes mixed with water, air, and living things, both plant and animal, and their remains. As man measures time, soil formation is extremely slow. Where the climate is moist and warm, it takes thousands of years to form just a few centimetres of soil. In cold or dry climates, it takes even longer, or soil may not form at all. While soil is technically a renewable resource, its slow rate of formation makes it practically irreplaceable. Soil is a dynamic mixture, forever changing as water comes and goes and plants and animals live and die. Wind, water, ice, and gravity move soil particles about, sometimes slowly, sometimes rapidly. But even though a soil changes, the layers of soil stay much the same during one human lifetime unless they are moved or scraped, or ploughed by man.   Soil teems with life All soil is full of life, and good soils are teeming with it. Plants and animals help keep the soil fertile. Plant roots tunnel through the soil and break it up, and decaying plants form humus. Burrowing animals mix the soil; the excrete of animals contribute nutrients and improve soil structure. Besides the soil's more obvious inhabitants, which include rodents, insects, mites, slugs and snails, spiders, and earthworms, there are countless microscopic residents, some helpful to man and his crops, some harmful. Good soils seem to hold the greatest populations of bacteria. Almost without exception, bacteria are involved in basic enzyme transformations that make possible the growth of higher plants, including our food crops. From man's point of view, bacteria may well be the most valuable of the life forms in soil. Chemical reactions occur in the soil as a result of exchange of positive ions, or cations. More exchanges take place in clay soils than in any other type. These chemical reactions are also essential to plant growth and development and are a good index of soil fertility.   Only a fraction of land is arable Man's chief interest in soil is for agriculture, but not all soils are suitable for farming. The total land area of the world exceeds 13 billion hectares, but less than half can be used for agriculture, including grazing. A much smaller fraction - about 1.4 billion hectares - is presently suitable for growing crops. The rest of the land is either too wet or too dry, too shallow or too rocky. Some is toxic or deficient in the nutrients that plants require and some is permanently frozen . Europe, Central America, and North America have the highest proportion of soils suitable for farming, although a number of the more developed countries seem intent on paving over much of their best farmland with roads and buildings. The lowest proportions of arable soils are in North and Central Asia, South America, and Australia. The single most serious drawback to farming additional land is lack of water.   Erosion destroyed civilizations Civilizations began where farming was most productive. When farm productivity declined, usually as a result of soil mismanagement, civilizations also declined - and occasionally vanished entirely. Of the three requisites for a thriving civilization: fertile soil, a dependable water supply and relatively level land with reasonable rainfall which would not cause erosion, it is likely that the third factor w


Who was director of the environmental pressure group Friends of the Earth 1984 - 90?

Our Board of Trustees | Forum for the Future Our Board of Trustees Keith Clarke CBE, Chair  Keith joined the board of Forum for the Future in 2011 and became chair in July 2012. He was formerly the chief executive of the global engineering and design consultancy, Atkins. Keith is a chartered architect with more than 40 years’ experience in construction and engineering. He is a non-executive director for Sirius Minerals plc, Chair of Future Cities Catapult and Tidal Lagoon Power plc, vice president of the Institute of Civil Engineers, patron of the Environmental Industries Commission at Oxford; and has Honorary Fellowships from the Royal Academy of Engineering, the Institution of Structural Engineers and Cardiff University.  He is also Visiting Professor for Sustainable Design at Aston University. Keith served as chairman of the UK Construction Industry Council (CIC) from 2008-10 after previously chairing its Health and Safety Committee.     Volker Beckers Volker has built up more than 20 years’ senior experience within the utility industry and has a comprehensive knowledge of European energy markets. He was Group CEO, RWE Npower plc until the end of 2012 and prior to this, its Group CFO from 2003 to 2009. He has worked in a variety of trade and industry bodies, including the CBI President’s Committee, on the Board of the German-British Chamber of Industry & Commerce, and since 1999 as Deputy Chair of the Executive Commercial Management Committee at the German Association of Energy and Water Industries (BDEW) and was also member of the Executive Committee of UKBCSE (now Energy UK). Since 2009 he chairs the Business Energy Forum.  Among various other non-Executive Directorships, Volker is currently non-executive Director, HM Revenue & Customs and Chair of its Scrutiny Committee. He also sits on the Advisory Board of the EU Centre for Energy and Resource Security (EUCERS) at King’s College and is Chair of the Advisory Board of Erasmus Centre for Future Energy Business at Rotterdam School of Management, Erasmus University.   Kelvyn Derrick OBE   Kelvyn has international business experience extending more than 40 years. Until 2007 he was the Chief Executive of Hamworthy plc , leading its transformation into an innovative technology company with international scope, and floating the company in 2004. Prior to that he was a founding partner of a private equity firm. In the past 15 years he has held many Non-Executive Director roles including Deputy Chair of the SW Regional Development Agency, Chair of the Society of Maritime Industries , Chair of Regen SW and a board member of the Bournemouth Symphony Orchestra . More recent roles include providing strategic advice to an innovative energy from waste group and trustee of Dorset Wildlife Trust . Kelvyn was awarded the OBE for services to engineering and international trade in the 2009 New Year’s Honours List.     Kate Levick Kate is head of government relations at the environmental charity CDP, leading work on regulatory engagement, public affairs and government fundraising in an international context. She previously worked at the UK Government Office of Climate Change helping to formulate domestic and international climate change policy, and at BP in a variety of commercial and environmental roles which included group environmental policy and strategy for low-carbon business in emerging markets. Kate has an MProf in Leadership for Sustainable Development from Forum for the Future.     Sara Parkin OBE Along with Jonathon Porritt and Paul Ekins, Sara is a founder of Forum for the Future for which she designed the Forum Masters in Leadership for Sustainable Development.  She taught the Masters for 20 years until 2016 when the University of Surrey University took it over, Forum deciding to develop a more flexible modular, international learning programme.  Together, the 250 graduates count as one of Forum for the Future’s greatest contribution to a sustainable future.   Sara’s 2010 book, based on the Forum Masters, The Positive Deviant: Sustainability Leadership in a Perverse Wor


Which European country is committed to decommissioning all of its nuclear reactors?

Nuclear Decommissioning: Decommission nuclear facilities - World Nuclear Association Decommissioning Nuclear Facilities (Updated November 2016) To date, about 110 commercial power reactors, 46 experimental or prototype reactors, over 250 research reactors and a number of fuel cycle facilities have been retired from operation. Some of these have been fully dismantled. Most parts of a nuclear power plant do not become radioactive, or are contaminated at only very low levels. Most of the metal can be recycled. Proven techniques and equipment are available to dismantle nuclear facilities safely and these have now been well demonstrated in several parts of the world. Decommissioning costs for nuclear power plants, including disposal of associated wastes, are reducing and contribute only a small fraction of the total cost of electricity generation. All power plants, coal, gas and nuclear, have a finite life beyond which it is not economically feasible to operate them. Generally speaking, early nuclear plants were designed for a life of about 30 years, though with refurbishment, some have proved capable of continuing well beyond this. Newer plants are designed for a 40 to 60 year operating life. At the end of the life of any power plant, it needs to be decommissioned, cleaned up and demolished so that the site is made available for other uses. For nuclear plants, the term decommissioning includes all clean-up of radioactivity and progressive dismantling of the plant. This may start with the owner's decision to write it off or declare that it is permanently removed from operation. For practical purposes it includes defueling and removal of coolant, though NRC at least defines it as strictly beginning only after fuel and coolant are removed. It concludes with licence termination after decontamination is verified and wastes removed. A Table showing about 150 shutdown reactors is at the end of this paper. About 17 of these have had the full decommissioning process completed as of 2016. Decommissioning Options The International Atomic Energy Agency (IAEA) has defined three options for decommissioning, the definitions of which have been internationally adopted: Immediate Dismantling (or Early Site Release/'Decon' in the US): This option allows for the facility to be removed from regulatory control relatively soon after shutdown or termination of regulated activities. Final dismantling or decontamination activities can begin within a few months or years, depending on the facility. Following removal from regulatory control, the site is then available for re-use. Safe Enclosure ('Safstor') or deferred dismantling: This option postpones the final removal of controls for a longer period, usually in the order of 40 to 60 years. The facility is placed into a safe storage configuration until the eventual dismantling and decontamination activities occur after resudual radioactivity has decayed. There is a risk in this case of regulatory change which could increase costs unpredictably. Entombment (or 'Entomb'): This option entails placing the facility into a condition that will allow the remaining on-site radioactive material to remain on-site without ever removing it totally. This option usually involves reducing the size of the area where the radioactive material is located and then encasing the facility in a long-lived structure such as concrete, that will last for a period of time to ensure the remaining radioactivity is no longer of concern. Each approach has its benefits and disadvantages. National policy determines which approach or combination of approaches is adopted or allowed. In the case of immediate dismantling (or early site release), responsibility for completion of decommissioning is not transferred to future generations. The experience and skills of operating staff can also be utilised during the decommissioning program. Alternatively, Safe Enclosure (or Safstor) allows significant reduction in residual radioactivity, thus reducing radiation hazard during the eventual dismantling. The expected improvements in mechanical techni


Effective Communication at Pepsi Co - Term Paper Effective Communication at Pepsi Co Which Indian state is at the eastern end of the Himalayas? A: Assam. What is the name of the atmospheric gas which screens out the sun's harmful ultraviolet radiation? A: Ozone. What is the world's deepest ocean? A: Pacific. Which is the largest animal ever to have inhabited the Earth? A: Blue Whale. What once covered 14% of the Earth's land area, but by 1991 over half had been destroyed? A: Rainforest. Which inland sea between Kazakhstan and Uzbekistan is fast disappearing because the rivers that feed it have been diverted and dammed? A: Aral Sea. The damaged Chernobyl nuclear power station is situated in which country? A: Ukraine. What type of rock is granite? A: Igneous. What type of rock is basalt? A: Igneous. What is the main constituent of natural gas? A: Methane. What is the term for nutrient enrichment of lakes? A: Eutrophication. Which of the Earth's atmospheric layers reflects radio waves? A: Ionosphere. Which gas forms 80% of Earth's atmosphere? A: Nitrogen. In which mountain chain would you find Mount Everest? A: Himalayas. What is the collective term for substances such as coal, oil and natural gas, the burning of which produces carbon dioxide? A: Fossil fuel. What contributes to the greenhouse effect at lower atmospheric levels, but in the upper atmosphere protects life on Earth? A: Ozone. What is the name of the process by which substances are washed out of the soil? A: Leaching. Who was director of the environmental pressure group Friends of the Earth 1984 - 90? A: Jonathon Porritt. Which European country is committed to decommissioning all of its nuclear reactors? A: Sweden. Which Canadian city gave its name to the 1987world agreement on protection of the ozone layer? A: Montreal. Five-legged creatures have damaged which 1250 mile long wonder of the world? A: Great Barrier Reef.


The dodo was a native bird of which island?

The Dodo Bird | History, Story and Resources for Dodobirds The Story of the Dodo Bird A Reference Site for The Dodo Bird and it's History The Dodo bird or Raphus Cucullatus was a flightless bird native to the island of Mauritius, near the island of Madagascar in the Indian Ocean. The closest relatives to the dodo bird are pigeons and doves, even though dodo birds were much larger in size. On average, dodo birds stood 3 feet tall and weighted about 40 lb. Unfortunately, due to aggressive human population, dodo birds became extinct in late 17th century. The Dodo Bird Location Dodo Birds, while now extinct, were found only on the small island of Mauritius, some 500 miles east of Madagascar, and 1200 miles east of Africa. The complete isolation of this island let the Dodo Birds grow and evolve without natural predators, unfortunately to a fault that led to their extinction.


What is the name given to the study of earthquakes?

earthquakes earthquakes adapted to HTML from lecture notes of Prof. Stephen A. Nelson Tulane University Earthquakes Earthquakes occur when energy stored in elastically strained rocks is suddenly released. This release of energy causes intense ground shaking in the area near the source of the earthquake and sends waves of elastic energy, called seismic waves, throughout the Earth. Earthquakes can be generated by bomb blasts, volcanic eruptions , and sudden slippage along faults. Earthquakes are definitely a geologic hazard for those living in earthquake prone areas, but the seismic waves generated by earthquakes are invaluable for studying the interior of the Earth. Origin of Earthquakes Most natural earthquakes are caused by sudden slippage along a fault zone . The elastic rebound theory suggests that if slippage along a fault is hindered such that elastic strain energy builds up in the deforming rocks on either side of the fault, when the slippage does occur, the energy released causes an earthquake. This theory was discovered by making measurements at a number of points across a fault. Prior to an earthquake it was noted that the rocks adjacent to the fault were bending. These bends disappeared after an earthquake suggesting that the energy stored in bending the rocks was suddenly released during the earthquake. Seismology, The Study of Earthquakes When an earthquake occurs, the elastic energy is released and sends out vibrations that travel throughout the Earth. These vibrations are called seismic waves. The study of how seismic waves behave in the Earth is called seismology. Seismographs - Seismic waves travel through the Earth as vibrations. A seismometer is an instrument used to record these vibrations and the resulting graph that shows the vibrations is called a seismograph. The seismometer must be able to move with the vibrations, yet part of it must remain nearly stationary. This is accomplished by isolating the recording device (like a pen) from the rest of the Earth using the principal of inertia. For example, if the pen is attached to a large mass suspended by a spring, the spring and the large mass move less than the paper which is attached to the Earth, and on which the record of the vibrations is made. Seismic Waves (freeware simulation 3.39Megs) . The source of an earthquake is called the focus, which is an exact location within the Earth were seismic waves are generated by sudden release of stored elastic energy. The epicenter is the point on the surface of the Earth directly above the focus. Sometimes the media get these two terms confused. Seismic waves emanating from the focus can travel in several ways, and thus there are several different kinds of seismic waves. Types of Seismic Waves Body Waves - emanate from the focus and travel in all directions through the body of the Earth. There are two types of body waves: P - waves - are Primary waves . They travel with a velocity that depends on the elastic properties of the rock through which they travel. Vp = Ö [(K + 4/3m )/r ] Where, Vp is the velocity of the P-wave, K is the incompressibility of the material, m is the rigidity of the material, and r is the density of the material. S-Waves - Secondary waves , also called shear waves. They travel with a velocity that depends only on the rigidity and density of the material through which they travel: Vs = Ö [( m )/r ] S-waves travel through material by shearing it or changing its shape in the direction perpendicular to the direction of travel. The resistance to shearing of a material is the property called the rigidity. It is notable that liquids have no rigidity, so that the velocity of an S-wave is zero in a liquid. (This point will become important later). Note that S-waves travel slower than P-waves, so they will reach a seismograph after the P-wave. Surface Waves - Surface waves differ from body waves in that they do not travel through the Earth, but instead travel along paths nearly parallel to the surface of the Earth. Surface waves behave like S-waves in that they cause up and down and side to side


Marble is formed by the metamorphosis of which rock?

Marble: Metamorphic Rock: Pictures, Definition, Properties Marble A non-foliated metamorphic rock that forms when limestone is subjected to heat and pressure. Pink Marble: A piece of pink marble about four inches (ten centimeters) across. The pink color is most likely derived from iron. Image by NASA. What is Marble? Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite (CaCO3) and usually contains other minerals, such as clay minerals, micas, quartz , pyrite , iron oxides, and graphite . Under the conditions of metamorphism, the calcite in the limestone recrystallizes to form a rock that is a mass of interlocking calcite crystals. A related rock, dolomitic marble, is produced when dolostone is subjected to heat and pressure.   Photo Gallery:   The Many Uses of Marble Ruby in Marble: Marble is often the host rock for corundum, spinel, and other gem minerals. This specimen is a piece of white marble with a large red ruby crystal from Afghanistan. Specimen is about 1 1/4 inches across (about 3 centimeters). Specimen and photo by Arkenstone / www.iRocks.com . How Does Marble Form? Most marble forms at convergent plate boundaries where large areas of Earth's crust are exposed to regional metamorphism. Some marble also forms by contact metamorphism when a hot magma body heats adjacent limestone or dolostone. Before metamorphism, the calcite in the limestone is often in the form of lithified fossil material and biological debris.  During metamorphism, this calcite recrystallizes and the texture of the rock changes. In the early stages of the limestone-to-marble transformation, the calcite crystals in the rock are very small. In a freshly-broken hand specimen, they might only be recognized as a sugary sparkle of light reflecting from their tiny cleavage faces when the rock is played in the light. As metamorphism progresses, the crystals grow larger and become easily recognizable as interlocking crystals of calcite.  Recrystallization obscures the original fossils and sedimentary structures of the limestone. It also occurs without forming foliation, which normally is found in rocks that are altered by the directed pressure of a convergent plate boundary. Recrystallization is what marks the separation between limestone and marble. Marble that has been exposed to low levels of metamorphism will have very small calcite crystals. The crystals become larger as the level of metamorphism progresses. Clay minerals within the marble will alter to micas and more complex silicate structures as the level of metamorphism increases. Marble Dimension Stone: Marble cut into blocks and slabs of specific size is known as "dimension stone." Photo © iStockphoto / Thomas Lehmann. Physical Properties and Uses of Marble Marble occurs in large deposits that can be hundreds of feet thick and geographically extensive. This allows it to be economically mined on a large scale, with some mines and quarries producing millions of tons per year. Most marble is made into either crushed stone or dimension stone. Crushed stone is used as an aggregate in highways, railroad beds, building foundations, and other types of construction. Dimension stone is produced by sawing marble into pieces of specific dimensions.  These are used in monuments, buildings, sculptures, paving and other projects. We have an article about " the uses of marble " that includes photos and descriptions of marble in many types of uses. Gray Marble: This specimen has calcite cleavage faces up to several millimeters in size that are reflecting light. The specimen is about two inches (five centimeters) across. Calcium carbonate medicines: Marble is composed of calcium carbonate. That makes it very effective at neutralizing acids. Highest purity marble is often crushed to a powder, processed to remove impurities, and then used to make products such as Tums and Alka-Seltzer that are used for the treatment of acid indigestion. Crushed marble is also used to reduce the acid cont


Which common water pollutant is believed to be harmful to newborn babies?

Common Newborn Ailments Common Newborn Ailments Comments Alexandra Grablewski Bringing a new baby home from the hospital is a very exciting time. It can also be pretty nerve-racking, especially for first-time moms. Rest assured that your baby is probably perfectly healthy. But keep in mind that there are some common conditions that your baby may experience. Most are nothing to worry too much about, but knowing what to expect can help you determine whether your baby might need medical attention. Read on for eight common conditions to find out what causes them, what to look for, and what treatment might be required. Then relax and enjoy your little one! Jaundice "Physiologic jaundice" is an indicator that a baby's blood contains an excess amount of bilirubin, a chemical formed during the normal breakdown of old red blood cells. We all have some bilirubin in our blood, but newborns usually have higher levels because their young immune system takes longer to process the extra red blood cells present at birth. Signs: A yellowish tint to the skin that usually appears first on the face and then on the chest, abdomen, and legs. To test, gently press on your baby's nose, forehead, or thigh to see if the skin beneath your finger appears yellow. Treatment: Jaundice usually corrects itself within a few days (though it may worsen before it gets better). If it doesn't, you child's pediatrician may do a blood test to determine the bilirubin level. If the level is extremely high and goes untreated, there is a chance that damage to the nervous system can occur. Your doctor may recommend phototherapy -- a treatment in which your baby is placed under special fluorescent-type lights for a day or two. Thrush Thrush is a common yeast infection. Signs: White patches in the mouth Treatment: Your pediatrician will most likely prescribe an oral antifungal medication. Heart Murmur A heart murmur is a noise heard between the beats of the heart. By listening to the heartbeat, doctors can usually classify the murmur by location and timing. Heart murmurs are extremely common, and almost always turn out to be harmless. Signs: A doctor will detect the heart murmur while listening to a baby's heart. Treatment: Normal or "innocent" heart murmurs usually don't require any treatment. If your child's pediatrician is concerned, though, he may refer you to a pediatric cardiologist for special tests. Cradle Cap Redness, greasy scales, and heavy flaking on the scalp are signs of cradle cap -- a condition caused by the buildup of oil and the shedding of skin cells. It looks unattractive, but isn't harmful to your baby. Signs: Scaly patches of skin cells and/or redness appear on the scalp. Treatment: You can treat cradle cap yourself by washing your baby's head with a mild baby shampoo more frequently than normal. Soft brushing can also help remove the scales. If this doesn't work, consult your pediatrician. She may prescribe a stronger shampoo or an ointment. Baby Acne Baby acne or pimples that break out on the face, typically during the fourth or fifth week of life, are harmless. Doctors believe the acne is caused by pregnancy hormones stimulating the oil glands in the skin. Signs: Baby acne looks similar to adult acne. Treatment: Gently wash your baby's face with mild baby soap once a day. Avoid laundering the crib sheets in harsh detergents. Umbilical Granuloma The stump of your baby's umbilical cord should dry up and fall off within a few weeks of birth. On occasion, the base of the cord forms a growth called a granuloma. Signs: The area around the umbilical cord may be moist and swell slightly. The area may be yellowish and could ooze or bleed a little bit. Treatment: Your pediatrician can treat the growth with silver nitrate to dry it out. If that doesn't work, it may have to be removed in a minor procedure. Umbilical Hernia An umbilical hernia is caused by a small hole in the abdominal wall that allows tissue to bulge out when there's pressure inside the abdomen (when a baby cries or strains, for example). Signs: Your baby's umbilical cord seems to push ou


What natural feature covers approximately 6% of the Earth's land surface, and harbors 40% of the Earth's species?

Community and Ecosystem Dynamics COMMUNITY AND ECOSYSTEM DYNAMICS Definitions | Back to Top A community is the set of all populations that inhabit a certain area. Communities can have different sizes and boundaries. These are often identified with some difficulty. An ecosystem is a higher level of organization the community plus its physical environment. Ecosystems include both the biological and physical components affecting the community/ecosystem. We can study ecosystems from a structural view of population distribution or from a functional view of energy flow and other processes. Community Structure | Back to Top Ecologists find that within a community many populations are not randomly distributed. This recognition that there was a pattern and process of spatial distribution of species was a major accomplishment of ecology. Two of the most important patterns are open community structure and the relative rarity of species within a community. Do species within a community have similar geographic range and density peaks? If they do, the community is said to be a closed community , a discrete unit with sharp boundaries known as ecotones . An open community, however, has its populations without ecotones and distributed more or less randomly. In a forest, where we find an open community structure, there is a gradient of soil moisture. Plants have different tolerances to this gradient and occur at different places along the continuum. Where the physical environment has abrupt transitions, we find sharp boundaries developing between populations. For example, an ecotone develops at a beach separating water and land. Open structure provides some protection for the community. Lacking boundaries, it is harder for a community to be destroyed in an all or nothing fashion. Species can come and go within communities over time, yet the community as a whole persists. In general, communities are less fragile and more flexible than some earlier concepts would suggest. Most species in a community are far less abundant than the dominant species that provide a community its name: for example oak-hickory, pine, etc. Populations of just a few species are dominant within a community, no matter what community we examine. Resource partitioning is thought to be the main cause for this distribution. Classification of Communities | Back to Top There are two basic categories of communities: terrestrial (land) and aquatic (water). These two basic types of community contain eight smaller units known as biomes . A biome is a large-scale category containing many communities of a similar nature, whose distribution is largely controlled by climate Terrestrial Biomes: tundra, grassland, desert,  taiga, temperate forest, tropical forest. Terrestrial biome  distribution is shown in Figure 1. Aquatic Biomes: marine,  freshwater. Figure 1. Major terrestrial     biomes. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer     Associates ( www.sinauer.com )     and WH Freeman ( www.whfreeman.com ),     used with permission. Terrestrial Biomes Tundra and Desert The tundra and desert biomes occupy the most extreme environments, with little or no moisture and extremes of temperature acting as harsh selective agents on organisms that occupy these areas. These two biomes have the fewest numbers of species due to the stringent environmental conditions. In other words, not everyone can live there due to the specialized adaptations required by the environment. Tropical Rain Forests Tropical rain forests occur in regions near the equator. The climate is always warm (between 20° and 25° C) with plenty of rainfall (at least 190 cm/year). The rain forest is probably the richest biome, both in diversity and in total biomass. The tropical rain forest has a complex structure, with many levels of life. More than half of all terrestrial species live in this biome. While diversity is high, dominance by a particular species is low. Typical tropical rain forest views are shown in Figure 2. While some animals live on the ground,


Trivia Questions for Environmental Science class. - ppt download Presentation is loading. Please wait. Trivia Questions for Environmental Science class. Published by Alexandrina Nicholson Modified about 1 year ago Embed Presentation on theme: "Trivia Questions for Environmental Science class."— Presentation transcript: 1 Trivia Questions for Environmental Science class 2 What is the name of the atmospheric gas which screens out the sun’s harmful UV radiation? a.Oxygen b.Ozone c.Carbon d.Carbon dioxide 3 What is the world’s deepest ocean? a.Pacific b.Atlantic c.Indian d.Arctic 4 Which is the largest animal ever to have inhabited the Earth? a.Blue whale b.Elephant c.Dinosaur d.Giraffe 5 In the United States, how many animals were on the threatened or endangered list as of 2009? a.200 b.750 c.1,200 d.900 6 What percentage of the world’s water is drinkable? a.20% b.60% c.1% d.100% 7 There is a specific name for rain, which contains chemicals that are harmful to the environment. What is this type of rain called? a.Acid pollution b.Acid rain c.Chemical rain d.Precipitation 8 If an item can decompose naturally, it is said to be this. a.Organic b.Biodegradable c.Renewable d.Environmentally friendly 9 Currently, the United States as a nation uses the most energy per annum. Which country comes in second? a.China b.Great Britain c.Japan d.Germany 10 The amount of energy that is saved for every 1,000 pounds of aluminum cans recycled is equivalent to how many gallons of gasoline? a.500 gallons b.1,250 gallons c.250 gallons d.100 gallons 11 Which of the following gases contribute to the effects of global warming? a.Methane b.Carbon dioxide c.Nitrous oxide d.All of these 12 DDT was once a common insecticide. However, it has been determined that it is incredibly harmful to the plant. Exactly, what does DDT affect? a.Water and air b.Soil and air c.Water and soil d.Air and crops 13 Soil erosion can have devastating effects on the planet. Erosion can be reversed by doing what? a.Re-forestation b.Increasing the number of animals in the region c.Re-introducing certain animal species d.Fertilizing soil 14 Littering and garbage removal is a major environmental concern. Which country was the first to implement a garbage removal system? a.United States b.Great Britain c.Germany d.Japan 15 In Canada, where temperatures are often cold, the average person does what with their car to five to ten minutes every day? a.Washes it b.Drives it c.Idles it d.Parks it 16 Fresh water is essential to life on the planet. Which country hosts the largest amount of fresh water? a.Russia b.Canada c.Brazil d.Kenya 17 What kind of animal is essential to more than 100,000 different species of plants? a.Spiders b.Birds c.Bees d.Frogs 18 Air pollution is on a rise. Scientists are able to monitor this increase using which kind of plant? a.Lichen b.Mushrooms c.Giant red woods d.Palm trees 19 What once covered 14% of the Earth’s land area, but by 1991 over half had been destroyed? a.Rainforest b.Oceans c.Mountains d.Sand 20 The damaged Chernobyl nuclear power station is situated in which country? a.Russia b.Ukraine c.Belarus d.Slovakia 21 What is the term for nutrient enrichment for lakes? a.Eutrophication b.Carrying capacity c.Nutrient deprivation d.Nitrification 22 What is the collective term for substances such as coal, oil and natural gas, the burning that produces carbon dioxide? a.Renewable resources b.Natural resources c.Fossil fuels d.Energy 23 Which gas forms 80% of Earths’ atmosphere? a.Oxygen b.Carbon c.Nitrogen d.Carbon dioxide 24 What name is given to the huge growths of algae sometimes seen in polluted lakes and rivers? a.Algal overgrowth b.Algal overproduction c.Algal bloom d.Algal pollution 25 What is the name of the process by which substances are washed out of the soil? a.Nutrient reduction b.Eutrophication c.Nutrient deprivation d.Leaching


What was the name of the dioxin-containing defoliant used during the Vietnam war by the USA army?

Agent Orange - Vietnam War - HISTORY.com Agent Orange A+E Networks Introduction Agent Orange was a powerful mixture of chemical defoliants used by U.S. military forces during the Vietnam War to eliminate forest cover for North Vietnamese and Viet Cong troops, as well as crops that might be used to feed them. The U.S. program of defoliation, codenamed Operation Ranch Hand, sprayed more than 19 million gallons of herbicides over 4.5 million acres of land in Vietnam from 1961 to 1972. Agent Orange, which contained the chemical dioxin, was the most commonly used of the herbicide mixtures, and the most effective. It was later revealed to cause serious health issues–including tumors, birth defects, rashes, psychological symptoms and cancer–among returning U.S. servicemen and their families as well as among the Vietnamese population. Google Operation Ranch Hand and Agent Orange From 1961 to 1972, the U.S. military conducted a large-scale defoliation program aimed at destroying the forest and jungle cover used by enemy North Vietnamese and Viet Cong troops fighting against U.S. and South Vietnamese forces in the Vietnam War . U.S. aircraft were deployed to spray powerful mixtures of herbicides around roads, rivers, canals and military bases, as well as on crops that might be used to supply enemy troops. During this process, crops and water sources used by the non-combatant peasant population of South Vietnam could also be hit. In all, Operation Ranch Hand deployed more than 19 million gallons of herbicides over 4.5 million acres of land. Did You Know? The controversy over Agent Orange and its effects has persisted for more than four decades. As late as June 2011, debate continued over whether so-called "Blue Water Navy" veterans (those who served aboard deep-sea vessels during the Vietnam War) should receive the same Agent Orange-related benefits as other veterans who served on the ground or on inland waterways. The most commonly used, and most effective, mixture of herbicides used was Agent Orange, named for the orange stripe painted on the 55-gallon drums in which the mixture was stored. It was one of several “Rainbow Herbicides” used, along with Agents White, Purple, Pink, Green and Blue. U.S. planes sprayed some 11 million to 13 million gallons of Agent Orange in Vietnam between January 1965 and April 1970. According to the U.S. Department of Veterans Affairs (VA), Agent Orange contained “minute traces” of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), more commonly known as dioxin. Through studies done on laboratory animals, dioxin has been shown to be highly toxic even in minute doses; human exposure to the chemical could be associated with serious health issues such as muscular dysfunction, inflammation, birth defects, nervous system disorders and even the development of various cancers. Agent Orange: Veteran Health Issues and Legal Battle Questions regarding Agent Orange arose in the United States after an increasing number of returning Vietnam veterans and their families began to report a range of afflictions, including rashes and other skin irritations, miscarriages, psychological symptoms, Type-2 diabetes, birth defects in children and cancers such as Hodgkin’s disease, prostate cancer and leukemia. In 1979, a class action lawsuit was filed on behalf of 2.4 million veterans who were exposed to Agent Orange during their service in Vietnam. Five years later, in an out-of-court-settlement, seven large chemical companies that manufactured the herbicide agreed to pay $180 million in compensation to the veterans or their next of kin. Various challenges to the settlement followed, including lawsuits filed by some 300 veterans, before the U.S. Supreme Court confirmed it in 1988. By that time, the settlement had risen to some $240 million including interest. In 1991, President George H.W. Bush signed into law the Agent Orange Act, which mandated that some diseases associated with defoliants (including non-Hodgkin’s lymphomas, soft tissue sarcomas and chloracne) be treated as the result of wartime service and helped codify the VA’


CITES is an international agreement on which environmental problem?

Verification of International Environmental Agreements - J.H. Ausubel and D.G. Victor Verification of International Environmental Agreements Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139 KEY WORDS: monitoring, compliance, regime Abbreviations used: BWU, blue whale unit; CEMS, continuous emissions monitoring systems; CFCs, chlorofluorocarbons; CFE, Treaty on Conventional Armed Forces in Europe; CITES, Convention on International Trade in Endangered Species; CTB, comprehensive test ban; EC, European Community; ECE, United Nations Economic Commission for Europe; EEZ, Exclusive Economic Zone; EMEP, Cooperative Programme for Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe; GAO, General Accounting Office (U.S. Congress); IAEA, International Atomic Energy Agency; ICES, International Council for the, Exploration of the Seas; IMCO, Inter-governmental Maritime Consultative Organization (IMCO after 1981); IMO, International Maritime Organization (IMCO before 1981); INF, Intermediate Nuclear Forces Treaty; IOS, International Observer System; IUCN, International Union for the Conservation of Nature (recently renamed to World Conservation Union); IWC, International Whaling Commission; LRTAP, Convention on Long Range Transboundary Air Pollution; LTB (T), Limited Test Ban (Treaty); MARPOL, Convention for the Prevention of Pollution from Ships; MSY, maximum sustainable yield; NAAQS, National Ambient Air Quality Standards (U.S.); NGOs, nongovernmental organizations; NEAFC, Northeast Atlantic Fisheries Commission; NPT, Nuclear Non-proliferation Treaty; NTM, national technical means; OECD, Organization for Economic Cooperation and Development; OSHA, Occupational Safety and Health Administration (U.S.); OSL, on-site inspection; OSIA, On-site Inspection Agency (U.S.); SALT, Strategic Arms Limitation Talks; TAC, total allowable catch; UNEP, United Nations Environment Programme. INTRODUCTION Problems and opportunities frequently cross national borders. Informal and formal international arrangements-loosely termed "regimes," defined here as systems of rule or government that have widespread influence--are for the collective management of such transboundary issues. Regimes are pervasive; their number and extent have grown markedly in the 20th century, especially since the Second World War. Students of the international system study the conditions under which regimes are formed and the factors that contribute to their success. These include distribution of power among states, the nature of the issue, its linkages to other issues, the roles and functions of international organizations, the processes of bargaining and rule-maldng, and the influence of domestic politics (1-3). Scholars also theorize how regimes are maintained and changed (4-6). In the past two decades students of international cooperation have increasingly applied their tools to issues of the environment and natural resources (7-9). A few studies have critically assessed international cooperation for transboundary environmental protection and drawn tentative conclusions on factors that lead to effective international regimes (8, 10-12). Studies of local management of common natural resources also yield relevant lessons for international environmental cooperation (13). For several reasons, assessing the effectiveness of international environmental agreements requires study of how compliance is verified. International agreements that are verifiable are more likely to succeed in both negotiation and implementation. The process of verification builds confidence in existing formal and informal agreements, thus improving the prospects for future cooperation and compliance. Verification activities produce information that can provide the technical basis for future agreements and shared understanding. Such information also can provide the basis for sanctions, which depend upon timely, legitimate, and accurate information. Information from verification activities helps to assess how effectively a regime has met its goals and whethe


What prevents the earth's atmosphere from floating out into space?

NOAA/NASA SciJinks :: Why does the atmosphere not drift off into space? Why does the atmosphere not drift off into space? The answer in a word is... Gravity Fortunately for us, Earth’s gravity is strong enough to hold onto its atmosphere. Mars, for example, is less than half Earth’s size and around one-tenth Earth’s mass. Less mass means less gravitational pull. Mars’ atmosphere is only about 1/100th as dense as Earth’s. And, by the way, it is mostly CO2. The air at the bottom of the atmosphere is under a lot more weight than the air nearer the top. Like the acrobat at the bottom of a stack of acrobats, the air at the bottom of the atmosphere is under a lot more weight than the air nearer the top. That means, the air nearer Earth’s surface is squished by the air above it, and is thus denser. The higher you go in the atmosphere, the thinner the air becomes. Ninety-nine percent of the air is in the lowest 30 kilometers (19 miles) of the atmosphere. Yes, Earth’s atmosphere has weight. So we, here at the surface, at the bottom of the “stack,” have about 14.7 pounds of air pressing down on every square inch of our bodies! Fortunately, we’re used to it. We evolved down here, so our bodies can handle it. Higher in the atmosphere we begin to have problems. Even at 3,000 — 4,500 meters (around 10 — 15,000 feet) altitude, the air becomes thin enough that most people have trouble getting enough oxygen. If Earth were the size of a beach ball, the breathable atmosphere would be as thin as paper. Seeing our atmosphere from space shows us how thin and fragile it is. "Many astronauts have reported seeing that delicate, thin blue aura at the horizon of the daylit hemisphere - that represents the thickness of the entire atmosphere - and immediately, unbidden, contemplating its fragility and vulnerability. They worry about it. They have reason to worry.” Carl Sagan, Billions & Billions If each acrobat weighs 100 pounds, how much weight does each acrobat hold up? Is there any wonder the bottom acrobat is starting to look a little squashed?


Which of the emissions from cars are acidic?

Vehicle Emission Controls Vehicle Emission Controls Think Energy Vehicle Emission Controls Through emissions of nitrogen oxides , cars and other road vehicles are major contributors to acidic emissions which cause acid rain. In all countries of the industrialised world, the number of vehicles on the roads has been continually increasing since the 1970s. With a large rise in traffic numbers, it becomes increasingly important to keep pollutant emissions to a minimum. There are presently a number of ways in which road traffic pollution can be reduced, including the use of emission control technology solutions. Since January 1993, all new cars sold in the European Union have been fitted with a catalytic converter. Most catalytic converters lead to a dramatic reduction in emissions of nitrogen oxides , as well as other harmful pollutants. Exhaust Gas Recirculation involves returning exhaust air to the fuel inlet, which results in a reduction in peak engine temperatures and emissions of nitrogen oxides from petrol vehicles. Smaller, lighter cars use less fuel and hence produce less pollution. Technological development using lighter materials for construction may therefore reduce emissions. The above technologies all provide a reduction in emissions from vehicles. Electric transport is an alternative development that could lead to a large reduction in acidic pollution at ground level, if it became more wide spread. Electric transport produces no emissions at the point of use, although pollution is emitted during the production of electricity from power stations . The main drawback for electric vehicles is the need to recharge batteries. In addition, although they have lower fuel and maintenance costs than petrol and diesel, at present they require a higher capital investment. The technical fixes such as those outlined above need to be combined with management schemes to reduce traffic in city centres, education to encourage the public to use their cars less, and the further development of alternative fuels that are not harmful to the environment.


Which quarry in the Italian region of Tuscany is renowned for the quality of its marble?

Tuscany Travel Guide Share The sunny Italian region of Tuscany provides infinite allure for travelers. Artists, winemakers, monks and merchants make their home in the rustic medieval hilltop hamlets, rolling hills of olives and wine, bucolic farmlands strewn with poppies and sunflowers, and marvelous cities such as Florence. Read on to discover our favorite Tuscan treasures. Florence – The Streets Less Traveled The large crowds that visit Florence in the summer can make it feel a bit like Disneyland. To find real Florentine flavor and space to breathe, cross one of the three bridges over the Arno River to the district. Less crowded than the other side, its medieval backstreets are a labyrinth of picturesque lanes, alleyways, nooks and crannies. While you should definitely try to see attractions like Pitti Palace , the lovely Boboli Garden and the lesser-known Bardini Gardens beyond it, when you get to Oltrarno, leave the map behind and just wander. Let yourself be surprised by narrow lanes that open onto a piazza, antique shops and artisan studios where contemporary craftsmen continue Florentine traditions such as sculpture, leathercraft, metalwork, woodwork, goldsmithing and bookbinding. Superb family-style trattorias feature fresh and simple ingredients—and are mostly undiscovered by tourists. Practice your Italian in small markets, cafés and gelaterias as you sample local specialties and explore piazzas like Santo Spirito and Piazza Pitti. Florence – Medieval Church with a Breathtaking View Signs lead the way to a medieval hilltop church beyond Oltrarno and the old city walls of Florence. The story of San Miniato al Monte goes back to 250 A.D., when St. Minias—an Armenian prince turned Christian hermit—was beheaded for his faith. Legend has it that St. Minias carried his own head over the Arno River and made his way up the hillside that overlooks Florence, where he laid himself to rest. The church was built in his honor in 1013, with an adjoining monastery erected around it. Michelangelo looked after the church during the Siege of Florence (1530), devising a plan of defense that included placing two cannons on top of the bell tower and hanging monks’ mattresses from its walls to absorb the impact from incoming cannonballs. Meticulously planned, the church is filled with fascinating symbolism , geometry and zodiacs (its façade resembles an owl). Impressive frescoes can be found inside and out. The adjoining gift shop sells honey, soap and liqueurs made by the monks. On summer weekdays, the monks accompany mass with Gregorian chants in the crypt at 5:30 p.m. Day or night, regardless of the season, the view is outstanding. Arezzo – A Medieval Pot of Gold Southeast of Florence, Arezzo presides on a hill overlooking four valleys. A haven of goldsmiths and jewelers, it’s also home to boutique shops and beautiful Renaissance and Romanesque architecture of red brick, stucco and stone. Monuments, churches and museums like the Casa di Giorgio Vasari provide historical and artistic interest, while small alleyways, piazzas, quiet streets and the Corso Italia—a pedestrian-only avenue to the old city center—make it a great, uncrowded place to explore on foot. The steeply graded Piazza Grande in the old town marks the center of this ancient commune and features a town hall that dates back to the 6th century. Take a seat at one of the surrounding cafés for a cool drink, gelato or panini. Pop into the town’s tavernas and trattorias to sample local specialties like acquacotta (peasant bread soup made with porcini mushrooms), ribollita (a bean and vegetable soup) and the famous Chianina steak (aka Bistecca Fiorentina), paired with one of the area’s fantastic wines. Summer events in Arezzo provide great souvenir shopping and entertainment. On the first Sunday of the first full weekend of each month, an antique fair is staged on the Piazza Grande. Spilling over to adjacent streets, hundreds of stalls offer everything from wrought-iron implements, cooking utensils and furniture to art prints, paintings, books and handblown glass. In June


What is the name given to the geological time period of 363-290 million years ago during which coal measures were formed?

Geologic Time Scale Geologic time scale From Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/Geologic_time_scale See notes at the ends of "Major events" about carbon dioxide concentrations. The geologic time scale is a chronologic schema (or idealized Model ) relating stratigraphy to time that is used by geologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of Earth . The table of geologic time spans presented here agrees with the dates and nomenclature proposed by the International Commission on Stratigraphy , and uses the standard color codes of the United States Geological Survey . Evidence from radiometric dating indicates that the Earth is about 4.570 billion years old. The geological or deep time of Earth's past has been organized into various units according to events which took place in each period. Graphical timelines The second and third timelines are each subsections of their preceding timeline as indicated by asterisks. Millions of Years The Holocene (the latest epoch ) is too small to be shown clearly on this timeline. Terminology Chron Generic term for any identifiable time period; not  necessarily part of a hierarchy The largest defined unit of time is the supereon, composed of eons. Eons are divided into eras, which are in turn divided into periods, epochs and ages. The terms eonothem , erathem , system , series , and stage are used to refer to the layers of rock that correspond to these periods of geologic time. Geologists tend to talk in terms of Upper/Late, Lower/Early and Middle parts of periods and other units , such as "Upper Jurassic ", and "Middle Cambrian ". Upper, Middle, and Lower are terms applied to the rocks themselves, as in "Upper Jurassic sandstone ," while Late, Middle, and Early are applied to time, as in "Early Jurassic deposition " or " fossils of Early Jurassic age." The adjectives are capitalized when the subdivision is formally recognized, and lower case when not; thus "early Miocene" but "Early Jurassic." Because geologic units occurring at the same time but from different parts of the world can often look different and contain different fossils, there are many examples where the same period was historically given different names in different locales. For example, in North America the Lower Cambrian is referred to as the Waucoban series that is then subdivided into zones based on trilobites . The same timespan is split into Tommotian , Atdabanian and Botomian stages in East Asia and Siberia . A key aspect of the work of the International Commission on Stratigraphy is to reconcile this conflicting terminology and define universal horizons that can be used around the world.[ citations needed ] History of the time scale See the main articles: history of geology and history of paleontology . Earth history mapped to 24 hours The first geologic time scale was proposed in 1913 by the British geologist Arthur Holmes . [2] He greatly furthered the newly created discipline of geochronology and published the world renowned book The Age of the Earth in 1913 in which he estimated the Earth 's age to be at least 1.6 billion years. [3] Aristotle realized that fossil seashells from rocks were similar to those found on the beach, indicating the fossils were once living animals. He deduced that the positions of land and sea had changed and these changes occurred over long periods of time. Leonardo da Vinci concurred with Aristotle's view that fossils were the remains of ancient life. [4] One of the principles underlying geologic time scales was the principle of superposition of strata, first proposed in the 11th century by the Persian geologist , Avicenna (Ibn Sina). However, he rejected the explanation of fossils as organic remains. [5] While discussing the origins of mountains in The Book of Healing in 1027, he outlined the principle as follows: [6] [7] "It is also possible that the sea may have happened to flow little by little over the land consisting of both plain and mountain, and then have ebbed awa


Which is further north, the tropic of cancer or the tropic of Capricorn?

The Equator, Tropic of Cancer and Tropic of Capricorn By Matt Rosenberg Updated August 31, 2016. Three of the most significant imaginary lines running across the surface of the Earth are the equator, the Tropic of Cancer, and the Tropic of Capricorn. While the equator is the longest line of latitude on the Earth (the line where the Earth is widest in an east-west direction), the tropics are based on the sun's position in relation to the Earth at two points of the year. All three lines of latitude are significant in their relationship between the Earth and the sun. The Equator The equator is located at zero degrees latitude . The equator runs through Indonesia, Ecuador, northern Brazil, the Democratic Republic of the Congo , and Kenya, among other countries . It is 24,901.55 miles (40,075.16 kilometers) long. On the equator, the sun is directly overhead at noon on the two equinoxes - near March and September 21. The equator divides the planet into the Northern and Southern Hemispheres. On the equator, the length of day and night are equal every day of the year - day is always twelve hours long and night is always twelve hours long. continue reading below our video Overview of the Four Seasons The Tropic of Cancer and The Tropic of Capricorn The Tropic of Cancer and the Tropic of Capricorn each lie at 23.5 degrees latitude. The Tropic of Cancer is located at 23.5° North of the equator and runs through Mexico, the Bahamas, Egypt, Saudi Arabia , India, and southern China. The Tropic of Capricorn lies at 23.5° South of the equator and runs through Australia, Chile, southern Brazil (Brazil is the only country that passes through both the equator and a tropic), and northern South Africa . The tropics are the two lines where the sun is directly overhead at noon on the two solstices - near June and December 21. The sun is directly overhead at noon on the Tropic of Cancer on June 21 (the beginning of summer in the Northern Hemisphere and the beginning of winter in the Southern Hemisphere) and the sun is directly overhead at noon on the Tropic of Capricorn on December 21 (the beginning of winter in the Northern Hemisphere and the beginning of summer in the Southern Hemisphere). The reason for the location of the Tropic of Cancer and the Tropic of Capricorn at 23.5° north and south respectively is due to the axial tilt of the Earth. The Earth is titled 23.5 degrees from the plane of the Earth's revolution around the sun each year. The area bounded by the Tropic of Cancer on the north and Tropic of Capricorn on the south is known as the "tropics." This area does not experience seasons because the sun is always high in the sky. Only higher latitudes, north of the Tropic of Cancer and south of the Tropic of Capricorn, experience significant seasonal variation in climate. Realize, however, that areas in the tropics can be cold. The peak of Mauna Kea on the big island of Hawaii stands nearly 14,000 feet above sea level, and snow is not unusual. If you live north of the Tropic of Cancer or south of the Tropic of Capricorn, the sun will never be directly overhead. In the United States, for example, Hawaii is the only location in the country that is south of the Tropic of Cancer, and it is thus the only location in the United States where the sun will be directly overhead in the summer.. Prime Meridian While the equator divides the Earth into Northern and Southern Hemispheres , it is the Prime Meridian at zero degrees longitude and the line of longitude opposite the Prime Meridian (near the International Date Line ) at 180 degrees longitude that divides the Earth into the Eastern and Western Hemispheres . The Eastern Hemisphere consists of Europe, Africa, Asia, and Australia while the Western Hemisphere includes North and South America . Some geographers place the boundaries between the hemispheres at 20° West and 160° East so as to not run through Europe and Africa. Unlike the equator and the Tropic of Cancer and the Tropic of Capricorn, the Prime Meridian and all lines of longitude are completely imaginary lines and have no significance w


What name is given to your angular distance on the Earth's surface relative to the equator?

Latitude and Longitude General Information CALCULATORS and CONVERTERS | Back Latitude and Longitude General Information The earth is effectively a sphere, so how do we describe where a point is on its surface? The most common way to locate points on the surface of the Earth is by standard, geographic coordinates called latitude and longitude. These coordinates values are measured in degrees (of arc, not temperature), and represent angular distances calculated from the center of the Earth. However, there are several CORRECT ways to designate them and to use the different values. What is latitude? We can imagine the Earth as a sphere, with an axis around which it spins. The ends of the axis are the North and South Poles. The Equator is a line around the earth, an equal distance from both poles. The Equator is also the latitude line given the value of zero degrees. This means it is the starting point for measuring latitude, up and down, or North and South properly indicated. Latitude values indicate the angular distance between the Equator and points North or South of it on the surface of the Earth. A line connecting all the points with the same latitude value is called a line of latitude. This term is usually used to refer to the lines that represent values in whole degrees. All lines of latitude are parallel to the Equator (and to each other), and they are sometimes also referred to as parallels. Parallels are equally spaced but they do NOT have the same distance around them! There are 90 degrees of latitude going North from the Equator, and the North Pole is at 90 degrees N. There are 90 degrees to the South of the Equator, and the South Pole is at 90 degrees S. Both are obviously the most distant points from any point on the Equator. When the directional designators (N, S, E or W) are omitted, northern latitudes are given positive values and southern latitudes are given negative values. The Prime Meridian is the alpha and omega of the lines of longitude, called meridians. They run perpendicular to lines of latitude, and all pass through both poles. Each longitude line is part of a great circle. There is no obvious zero degree point for longitude, as there is for latitude. Throughout history many different starting points have been used to measure longitude. By international agreement, the meridian line through Greenwich, England, is currently given the value of zero degrees of longitude; this meridian is referred to as the Prime Meridian. Longitude values are indicate the angular distance between the Prime Meridian and points east or west of it on the surface of the Earth. The Earth is divided equally into 360 degrees of longitude. There are 180 degrees of longitude to the east of the Prime Meridian; when the directional designator is omitted these longitudes are given positive values. There are also 180 degrees of longitude to the west of the Prime Meridian; when the directional designator is omitted these longitudes are given negative values. The 180 degree longitude line is opposite the Prime Meridian on the globe, and is the same going either east or west. How precise can we be with latitude and longitude? Degrees of latitude and longitude can be further subdivided into minutes and seconds (units of arc, not time): There are 60 minutes (') per degree, and 60 seconds (") per minute. For example, a coordinate might be written 65° 32' 15". Degrees can also be expressed as decimals: 65.5375, degrees and decimal minutes: 65° 32.25', or even degrees, minutes, and decimal seconds: 65° 32' 15.275". All these notations allow us to locate places on the Earth quite precisely – to within inches, depending on the accuracy of the equipment doing the measurement. A degree of latitude is approximately 69 miles, and a minute of latitude is approximately 1.15 miles. A second of latitude is approximately 0.02 miles, or just over 100 feet. A degree of longitude varies in size. At the equator, it is approximately 69 miles, the same size as a degree of latitude. The size gradually decreases to zero as the meridians converge at the poles.


Which landlocked Asian country is described as the world's 'highest rubbish dump' because of all the refuse left behind by expeditions?

Asia Times Online :: Letters     Letters      Please provide your name or a pen name, and your country of residence.             Lengthy letters run the risk of being cut. Please note: This Letters page is intended primarily for            readers to comment on ATol articles or related issues. It should not be used as            a forum for readers to debate with each other. The Edge is the place for that. The editors do not mind publishing one            or two responses to a reader's letter, but will, at their discretion, direct            debaters away from the Letters page. Letters 2013 [Re Jeju port rises to territorial challenge , Dec 19, 2013] Sung Chan Kim and Seok-ho Kang swiftly concludes the obvious as a response to China's initiative in the South Asia Sea. They are too quick to pat themselves on the back. The construction of a military industrial port on Jeju was quickly understood from the very germ of the idea. In other words, South Korea had China very much in its cross hairs. Now that Beijing is flexing crudely its geopolitical muscle, South Korea rushes into to proclaim to the world see how prescient we were to anticipate China's moves. Stuff and nonsense, since Seoul and its US protector's project initially was a red flag to a resurgent China. Nakamura Junzo Guam (Dec 20, '13) [Re China vs US 'sea-to-shining-sea' , Dec 18, '13] Letďż˝s see. US Vice President Joe Biden was in China a couple weeks ago; coincidentally, Apple Inc announced a tentative partnership with China Mobile, thereby greatly increasing the devices companyďż˝s potential customer base. Seems both the Americans and the Chinese understand very well that (geo)politics largely serves economics. On the other hand, the countries that fail to fully grasp this relationship will likely be left holding an empty bag once the economic train has left the station. (But I suppose they all can feel good about themselves by patting one another on the back.) John Chen USA (Dec 20, '13) [Re Uyghurs shot dead in Xinjiang violence , Dec 19, '13] I do not know what type of veil would be used by a Uyghur Chinese woman though there are Muslim fundamentalists who cover their whole face except for the pair of eyes. If this was the case, the police have the right to lift the veil to identify the person. The police chief, Memet Sidiq, must have known the tradition as he himself is a Uyghur Chinese. Besides, attacking police is never allowed in any country, not even in the US. This is the third article submitted by RFA's Uyghur Service on this issue. They have made Asia Times Online a forum to justify their violent acts. Wendy Cai United States (Dec 20, '13) Some time next year the US will "officially" withdraw its armed forces from Afghanistan. I doubt that we'll see the last commanding Amerikan general cross a bridge behind a tank like the Soviets did in 1989, or see TV images of hapless Amerikans and luckless Afghans climbing desperately onto fleeing helicopters from the Kabul Embassy roof a la Saigon 1975. Of course, the Empire is not about to abandon a 13 year war without some kind of intelligence and military presence remaining behind, if for no other reason than to act as a figleaf to mask the debacle. But make no mistake about it; the Empire has been decisively defeated, if not humiliated, by the ragtag Afghan insurgency and its not-so-invisible supporters. The humiliation comes not so much for the fact that the allegedly mightiest military machine in the history of planet earth was unable to quell a fifth rate insurrection in the Third World (Vietnam had already proven that was possible) as from the fact that our alleged most important regional allies, Saudi Arabia and Pakistan, betrayed, manipulated and subverted every move we made in Afghanistan, with impunity, gall and, in the case of Pakistan, an open hand demanding ever more money, weapons and political support. They played Uncle Sam for the sucker he still very much is. Both Muslim countries actively funded, supported and trained the Ta


What name is given to the layer of the atmosphere closest to the surface of the Earth?

Layers of the Atmosphere Layers of the Atmosphere By Matt Rosenberg Updated October 20, 2016. The earth is surrounded by the atmosphere, which is the body of air or gasses that protects the planet and enables life. Most of our atmosphere is located close to the earth's surface where it is most dense. The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gasses. There are five distinct layers of the earth. Let's look at each, from closest to farthest from the earth. Troposphere The layer of the atmosphere closest to the earth is the troposphere. This layer is where weather occurs. It begins at the surface of the earth and extends out to about 4-12 miles. The temperature of the troposphere decreases with height. This layer is known as the lower atmosphere. Stratosphere Above the troposphere is the stratosphere, which extends to about 30-35 miles above the earth's surface. Temperature rises within the stratosphere but still remains well below freezing. Mesosphere From about 35 to 50 miles above the surface of the earth lies the mesosphere, where the air is especially thin and molecules are great distances apart. continue reading below our video What are the Seven Wonders of the World Temperatures in the mesosphere reach a low of -184°F (-120°C). The stratosphere and the mesosphere are the middle atmospheres. Thermosphere The thermosphere rises several hundred miles above the earth's surface, from 50 miles up to about 400 miles. Temperature increases with height and can rise to as high as 3,600°F (2000°C). Nonetheless, the air would feel cold because the hot molecules are so far apart. This layer is known as the upper atmosphere. Exosphere Extending from the top of the thermosphere to 6200 miles (10,000 km) above the earth is the exosphere. This layer has very few atmospheric molecules, which can escape into space. Pauses Between each layer of the atmosphere is a boundary. Above the troposphere is the tropopause; above the stratosphere is the stratopause; above the mesosphere is the mesopause; and above the thermosphere is the thermopause. At these "pauses," maximum change between the "spheres" occur.


What name is given to the Earth's single continent, which existed 250 million years ago?

The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. You have new items in your feed. Click to view. Question and answer The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. The name of the Earth's single continent was B. Pangaea Get an answer The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. Original conversation User: The name of Earth's single, huge continent from over 250 million years ago is (1 point) A.Megaland. B.Pangaea. C.Gondwanaland. D.Laurasia. Weegy: The name of the Earth's single continent was B. Pangaea MrG |Points 1812| User: Krystal Weegy: The name of Earth's single, huge continent from over 250 million years ago is B.- Pangaea Expert answered| hhaokok |Points 32|


What component of CFCs causes destruction of ozone?

NASA Earth Observatory (Illustration courtesy Barbara Summey, SSAI)   Understanding Stratospheric Ozone Depletion    Our understanding of stratospheric ozone depletion has been obtained through a combination of laboratory studies, computer models, and atmospheric observations. The wide variety of chemical reactions that occur in the stratosphere have been discovered and studied in laboratory studies. Chemical reactions between two gases follow well-defined physical rules. Some of these reactions occur on the surfaces of polar stratospheric clouds (PSCs) formed in the winter stratosphere. Reactions have been studied that involve many different molecules containing chlorine, bromine, fluorine, and iodine and other atmospheric constituents such as carbon, oxygen, nitrogen, and hydrogen. These studies have shown that several reactions involving chlorine and bromine directly or indirectly destroy ozone in the stratosphere.    Computer models have been used to examine the combined effect of the large group of known reactions that occur in the stratosphere. These models simulate the stratosphere by including representative chemical abundances, winds, air temperatures, and the daily and seasonal changes in sunlight. These analyses show that under certain conditions chlorine and bromine react in catalytic cycles in which one chlorine or bromine atom destroys many thousands of ozone molecules. Models are also used to simulate ozone amounts observed in previous years as a strong test of our understanding of atmospheric processes and to evaluate the importance of new reactions found in laboratory studies. The responses of ozone to possible future changes in the abundances of trace gases, temperatures, and other atmospheric parameters have been extensively explored with specialized computer models .    Atmospheric observations have shown what gases are present in different regions of the stratosphere and how their abundances vary. Gas and particle abundances have been monitored over time periods spanning a daily cycle to decades. Observations show that halogen source gases and reactive halogen gases are present in the stratosphere at the amounts required to cause observed ozone depletion. Ozone and chlorine monoxide (ClO), for example, have been observed extensively with a variety of instruments. ClO is a highly reactive gas that is involved in catalytic ozone destruction cycles throughout the stratosphere . Instruments on the ground and on satellites, balloons, and aircraft now routinely detect ozone and ClO remotely using optical and microwave signals. High-altitude aircraft and balloon instruments are also used to detect both gases locally in the stratosphere . The observations of ozone and reactive gases made in past decades are used extensively in comparisons with computer models in order to increase confidence in our understanding of stratospheric ozone depletion.   The stratospheric ozone layer shields life on Earth from the Sun’s harmful ultraviolet radiation. Chemicals that destroy ozone are formed by industrial and natural processes. With the exception of volcanic injection and aircraft exhaust, these chemicals are carried up into the stratosphere by strong upward-moving air currents in the tropics. Methane (CH4), chlorofluorocarbons (CFCs), nitrous oxide (N2O) and water are injected into the stratosphere through towering tropical cumulus clouds. These compounds are broken down by the ultraviolet radiation in the stratosphere. Byproducts of the breakdown of these chemicals form “radicals”—such as nitrogen dioxide (NO2) and chlorine monoxide (ClO)—that play an active role in ozone destruction. Aerosols and clouds can accelerate ozone loss through reactions on cloud surfaces. Thus, volcanic clouds and polar stratospheric clouds can indirectly contribute to ozone loss.       Stratospheric air temperatures in both polar regions reach minimum values in the lower stratosphere in the winter season. Average minimum values over Antarctica are as low as –90°C in July and August in a ty


What Does a Barometer Measure? | Wonderopolis Wonder of the Day #213 What Does a Barometer Measure? What does a barometer measure? How much pressure does the atmosphere exert on you at all times? How do changes in air pressure signal changes in the weather? Tags: Listen Can you feel the pressure ? It's around you…all the time…everywhere you go. What is it? Atmospheric pressure — often referred to simply as air pressure — is the constant force exerted on you by the weight of little particles of air. These tiny air particles, called air molecules, can't be seen, but they are all around you. They have weight, which means they constantly “push" down on you. If you look straight up in the air, you can imagine a tall column of air above your head reaching all the way to the edge of the Earth's atmosphere . The weight of that column of air is the amount of air pressure exerted on you. If you move to a higher elevation (climb a mountain, for example), the air pressure will be lower. Why? The length of that column of air above you has decreased by the amount of your increase in elevation . As you move to a higher elevation , you may notice that your ears have to “pop." This balances the pressure between the inside and outside of your ear. Since there are fewer air molecules the higher you go, you will also probably need to breathe faster to breathe in more molecules to make up for the deficit . Air molecules also take up space. Because there tends to be a lot of empty space between air molecules, air can either fill a big area or it can be compressed to fit into a smaller area. When it's compressed, air is said to be under high pressure . Earth's atmosphere presses down on you with a force of almost 15 pounds per square inch. You may be wondering why it doesn't feel that heavy or why you're not crushed under the weight. Remember that thing you do called breathing? The air inside your body balances out the pressure from air in the atmosphere , which prevents you from being squished by the pressure of the atmosphere . You don't sense air pressure as a constant force , because the air inside you balances outside pressure and you're used to that feeling. If you watch the weather report frequently, you're sure to hear the weatherman talk about barometric pressure . Weather forecasters use a special tool called a barometer to measure air pressure . Barometers measure atmospheric pressure using mercury , water or air. You'll usually hear forecasters give measurements in either inches of mercury or in millibars (mb). Forecasters use changes in air pressure measured with barometers to predict short-term changes in the weather . Changes in air pressure signal the movement of high- or low- pressure areas of air, called fronts. Air molecules in high pressure areas tend to flow toward low pressure areas. We call this flow of air molecules wind . The larger the difference in pressure between areas, the stronger the winds will be. As weather forecasters monitor air pressure , falling barometer measurements can signal that bad weather is on the way. In general, if a low pressure system is on its way, be prepared for warmer weather with storms and rain. If a high pressure system is coming, you can expect clear skies and cooler temperatures. Wonder Words (18) Test your knowledge Wonder What's Next? We’re about to erupt with excitement. Join us in Wonderopolis tomorrow for a Wonder of the Day that will blow your top! Try It Out How's the weather? Gather together a few friends or family members to check out one or more of the following fun activities: How accurate is the weatherman where you live? Keep track and find out! Over the course of the next week, watch the weather report at the same time each day. Take notes in a journal. Make sure to record predictions for temperature and precipitation. Then make careful observations about the weather on your own. Did the weatherman get it right? How often? Would you like to be a weather forecaster one day? Why or why not? Are you ready to predict the weather? You can be a weather forecaster in the making


What is the basic chemical composition of malachite?

Malachite: Uses and properties of the mineral and gemstone Home » Minerals » Malachite Malachite Used as an ore of copper, a pigment, a gemstone, and a sculptural material for thousands of years. Malachite Gemstones: A malachite cabochon (30x40 millimeter) and a malachite puffed heart, both cut from rough mined in the Democratic Republic of the Congo. This oval cabochon shows the agate-like banding in various shades of green that is typical of malachite. The puffed heart shows concentric structures. What is Malachite? Malachite is a green copper carbonate hydroxide mineral with a chemical composition of Cu2(CO3)(OH)2. It was one of the first ores used to produce copper metal. It is of minor importance today as an ore of copper because it is usually found in small quantities and can be sold for higher prices for other types of use. Malachite has been used as a gemstone and sculptural material for thousands of years and is still popular today. Today it is most often cut into cabochons or beads for jewelry use. Malachite has a green color that does not fade over time or when exposed to light. Those properties, along with its ability to be easily ground to a powder, made malachite a preferred pigment and coloring agent for thousands of years. Botryoidal Malachite: Close-up of botryoidal malachite in a seafoam green color from Bisbee, Arizona. This view spans an area of the specimen about 5 millimeters wide and high. Specimen and photo by Arkenstone / www.iRocks.com . Where Does Malachite Form? Malachite is a mineral that forms at shallow depths within the Earth, in the oxidizing zone above copper deposits. It precipitates from descending solutions in fractures, caverns, cavities, and the intergranular spaces of porous rock. It often forms within limestone where a subsurface chemical environment favorable for the formation of carbonate minerals can occur. Associated minerals include azurite , bornite , calcite , chalcopyrite , copper , cuprite , and a variety of iron oxides. Some of the first malachite deposits to be exploited were located in Egypt and Israel. Over 4000 years ago, they were mined and used to produce copper. Material from these deposits was also used to produce gemstones, sculptures, and pigments. Several large deposits in the Ural Mountains of Russia were aggressively mined, and they supplied abundant gem and sculptural material in the 1800s. Very little is produced from these deposits today. Much of the malachite entering the lapidary market today is from deposits in the Democratic Republic of the Congo. Smaller amounts are produced in Australia, France, and Arizona. Stalactitic malachite: A specimen of stalactitic malachite from the Kasompi Mine, Democratic Republic of the Congo. The specimen is approximately 21 x 16 x 12 centimeters in size. Specimen and photo by Arkenstone / www.iRocks.com . Physical Properties of Malachite A minor ore of copper. Gemstones, small sculptures, pigment. Physical Properties of Malachite Malachite's most striking physical property is its green color. All specimens of the mineral are green and range from a pastel green, to a bright green, to an extremely dark green that is almost black. It is typically found as stalactites and botryoidal coatings on the surfaces of underground cavities - similar to the deposits of calcite found in caves. When these materials are cut into slabs and pieces, the sawn surfaces often exhibit banding and eyes that are similar to agate . Malachite is rarely found as a crystal, but when found, the crystals are usually acicular to tabular in shape. The crystals are bright green in color, translucent, with a vitreous to adamantine luster. Non-crystalline specimens are opaque, usually with a dull to earthy luster. Malachite is a copper mineral, and that gives malachite a high specific gravity that ranges from 3.6 to 4.0. This property is so striking for a green mineral that malachite is easy to identify. Malachite is one of a small number of green minerals that produces effervescence in contact with cold, dilute hydrochloric acid . It


What is the term for a fold of the Earth's crust in which the layers of rock dip inwards?

10(l) Crustal Deformation Processes: Folding and Faulting CHAPTER 10: Introduction to the Lithosphere   (l). Crustal Deformation Processes: Folding and Faulting The topographic map illustrated in Figure              10l-1 suggests that the Earth's surface has been              deformed. This deformation is the result of forces              that are strong enough to move ocean sediments to an              eleveation many thousands meters above sea level. In              previous lectures, we have discovered that this displacement              of rock can be caused by tectonic              plate movement and subduction , volcanic              activity , and intrusive igneous activity . Figure 10l-1: Topographic                 relief of the Earth's terrestrial surface and                 ocean basins. Ocean trenches and the ocean floor                 have the lowest elevations on the image and are                 colored dark blue. Elevation is indicated by                 color. The legend below shows the relationship                 between color and elevation. (Source: National                 Geophysical Data Center , National Oceanic                 and Atmospheric Administration).   Deformation of rock involves changes in             the shape and/or volume of these substances. Changes             in shape and volume occur when stress and strain causes             rock to buckle and fracture or crumple into folds. A fold can             be defined as a bend in rock that is the response to             compressional forces. Folds are most visible in rocks             that contain layering. For plastic deformation of rock             to occur a number of conditions must be met, including: The rock material must have the ability to deform               under pressure and heat. The higher the temperature of the rock the more               plastic it becomes. Pressure must not exceed the internal strength               of the rock. If it does, fracturing occurs. Deformation must be applied slowly. A number of different folds have             been recognized and classified by geologists. The simplest             type of fold is called a monocline (Figure             10i-2). This fold involves a slight bend in otherwise             parallel layers of rock. Figure 10l-2: Monocline             fold.   An anticline is             a convex up fold in rock that resembles an arch like             structure with the rock beds (or limbs) dipping way             from the center of the structure (Figure 10l-3). Figure 10l-3: Anticline               fold. Note how the rock layers dip away from the               center of the fold are roughly symmetrical.   A syncline is             a fold where the rock layers are warped downward (Figure             10l-4 and 10l-5). Both anticlines and synclines             are the result of compressional stress. Figure 10l-4: Syncline               fold. Note how the rock layers dip toward the center               of the fold and are roughly symmetrical.   Figure 10l-5: Synclinal                folds in bedrock, near Saint-Godard-de-Lejeune,                Canada. (Source: Natural                Resources Canada - Terrain Sciences Division -                Canadian Landscapes ).   More complex fold types can develop in             situations where lateral pressures become greater. The             greater pressure results in anticlines and synclines that             are


Which clouds only occur above 10,000 meters?

Clouds - Metlink Teaching Weather and Climate Clouds Cirriform clouds   The nature of clouds A classification of clouds was introduced by Luke Howard (1772-1864) who used Latin words to describe their characteristics. Cirrus – a tuft or filament (e.g. of hair) Cumulus – a heap or pile Stratus – a layer Nimbus – rain bearing There are now ten basic cloud types with names based on combinations of these words (the word ‘alto’, meaning high but now used to denote medium-level cloud, is also used). C.S. Broomfield (© Crown Copyright) Clouds form when moist air is cooled to such an extent that it becomes saturated. The main mechanism for cooling air is to force it to rise. As air rises it expands – because the pressure decreases with height in the atmosphere – and this causes it to cool. Eventually it may become saturated and the water vapour then condenses into tiny water droplets, similar in size to those found in fog, and forms cloud. If the temperature falls below about minus 20 °C, many of the cloud droplets will have frozen so that the cloud is mainly composed of ice crystals. The main ways in which air rises to form cloud Rapid local ascent when heated air at the earth’s surface rises in the form of thermal currents (convection). Slow, widespread, mass ascent where warm moist air is forced to rise above cold air. The region between warm and cold air is called a ‘front’. Upward motion associated with turbulent eddies resulting from the frictional effect of the earth’s surface. Air forced to rise over a barrier of mountains or hills. The first of these tends to produce cumulus-type clouds, whereas the next two usually produce layered clouds. The last can produce either cumulus-type cloud or layered cloud depending upon the state of the atmosphere. The range of ways in which clouds can be formed and the variable nature of the atmosphere give rise to the enormous variety of shapes, sizes and textures of clouds. Types of cloud The ten main types of cloud can be separated into three broad categories according to the height of their base above the ground: high clouds, medium clouds and low clouds. High clouds are usually composed solely of ice crystals and have a base between 18,000 and 45,000 feet (5,500 and 14,000 metres). Cirrus – white filaments Cirrocumulus – small rippled elements Cirrostratus – transparent sheet, often with a halo Medium clouds are usually composed of water droplets or a mixture of water droplets and ice crystals, and have a base between 6,500 and 18,000 feet (2,000 and 5,500 metres). Altocumulus – layered, rippled elements, generally white with some shading Altostratus – thin layer, grey, allows sun to appear as if through ground glass Nimbostratus – thick layer, low base, dark. Rain or snow falling from it may sometimes be heavy Low clouds are usually composed of water droplets – though cumulonimbus clouds include ice crystals – and have a base below 6,500 feet (2,000 metres). Stratocumulus – layered, series of rounded rolls, generally white with some shading Stratus – layered, uniform base, grey Cumulus – individual cells, vertical rolls or towers, flat base Cumulonimbus – large cauliflower-shaped towers, often ‘anvil tops’, sometimes giving thunderstorms or showers of rain or snow Most of the main cloud types can be subdivided further on the basis of shape, structure and degree of transparency. Cumulus Cumulus clouds are often said to look like lumps of cotton wool. With a stiff breeze, they march steadily across the sky; their speed of movement gives a clue to their low altitude. Cumulus clouds occasionally produce light showers of rain or snow. © Steve Jebson © Steve Jebson Typically, the base of cumulus clouds will be about 2,000 feet (600 metres) above ground in winter, and perhaps 4,000 feet (1,200 metres) or more on a summer afternoon. Individual clouds are often short-lived, lasting only about 15 minutes. They tend to form as the ground heats up during the day and become less frequent as the sun’s heat wanes towards evening. The cause of small cumulus clouds is usually convection. Heat from t