Atmosphere & Air Pollution Quiz Review

explain what causes wind

Air movement takes place in the troposphere. This is the lowest layer of the atmosphere. Air moves because of differences in heating. These differences create convection currents and winds. Air in the troposphere is warmer near the ground. The warm air rises because it is light. The light, rising air creates an area of low air pressure at the surface. The rising air cools as it reaches the top of the troposphere. The air gets denser, so it sinks to the surface. The sinking, heavy air creates an area of high air pressure near the ground. Air always flows from an area of higher pressure to an area of lower pressure. Air flowing over Earth's surface is called wind. The greater the difference in pressure, the stronger the wind blows.

what causes a monsoon?

Monsoons are like land and sea breezes, but on a larger scale. They occur because of seasonal changes in the temperature of land and water. In the winter, they blow from land to water. In the summer, they blow from water to land. In regions that experience monsoons, the seawater offshore is extremely warm. The hot air absorbs a lot of the moisture and carries it over the land. Summer monsoons bring heavy rains on land. Monsoons occur in several places around the globe. The most important monsoon in the world is in southern Asia. These monsoons are important because they carry water to the many people who live there.

describe how and why temperature changes with altitude in the atmosphere

Air temperature changes as altitude increases. In some layers of the atmosphere, the temperature decreases. In other layers, it increases. The troposphere is the lowest layer of the atmosphere. In it, temperature decreases with altitude. The troposphere gets some of its heat directly from the Sun. Most, however, comes from Earth's surface. The surface is heated by the Sun and some of that heat radiates back into the air. This makes the temperature higher near the surface than at higher altitudes. At the top of the troposphere is a thin layer of air called the tropopause. This layer acts as a barrier. It prevents cool air in the troposphere from mixing with warm air in the stratosphere. Air temperature in the stratosphere layer increases with altitude. The stratosphere gets most of its heat from the Sun. Therefore, it's warmer closer to the Sun. The air at the bottom of the stratosphere is cold. The cold air is dense, so it doesn't rise. As a result, there is little mixing of air in this layer. At the top of the stratosphere is a thin layer called the stratopause. It acts as a boundary between the stratosphere and the mesosphere. The mesosphere is the layer above the stratosphere. Temperature decreases with altitude in this layer. There are very few gas molecules in the mesosphere. This means that there is little matter to absorb the Sun's rays and heat the air. Most of the heat that enters the mesosphere comes from the stratosphere below. That's why the mesosphere is warmest at the bottom. At the top of the mesosphere is the mesopause. Temperatures here are colder than anywhere else in the atmosphere. Nowhere on Earth's surface is it as cold. The thermosphere is the layer above the mesosphere. Temperature increases with altitude in the thermosphere. The Sun's energy there is very strong. The molecules absorb the Sun's energy and are heated up. But there are so very few gas molecules, that the air still feels very cold. The exosphere is the layer above the thermosphere. This is the top of the atmosphere. The exosphere has no real upper limit; it just gradually merges with outer space. Gas molecules are very far apart in this layer, but they are really hot. Earth's gravity is so weak in the exosphere that gas molecules sometimes just float off into space.

explain how density and air pressure change with altitude

Altitude is height above sea level. The density of air decreases with height. There are two reasons. At higher altitudes, there is less air pushing down from above. Also, gravity is weaker farther from Earth's center. So at higher altitudes, air molecules can spread out more and air density decreases.

why do global winds curve instead of moving straight north or south?

Earth is hottest at the equator and gets cooler toward the poles. The differences in heating create huge convection currents in the troposphere. At the equator, for example, warm air rises up to the tropopause. It can't rise any higher, so it flows north or south. By the time the moving air reaches 30° N or S latitude, it has cooled. The cool air sinks to the surface. Then it flows over the surface back to the equator. Other global winds occur in much the same way. There are three enormous convection cells north of the equator and three south of the equator. Earth is spinning as air moves over its surface. This causes the Coriolis effect. Winds blow on a diagonal over the surface, instead of due north or south. From which direction do the northern trade winds blow? Without Coriolis Effect the global winds would blow north to south or south to north. But Coriolis makes them blow northeast to southwest or the reverse in the Northern Hemisphere. The winds blow northwest to southeast or the reverse in the southern hemisphere. The wind belts have names. The Trade Winds are nearest the equator. The next belt is the westerlies. Finally are the polar easterlies. The names are the same in both hemispheres.

what is a jet stream and which way do they move?

Jet streams are fast-moving air currents high in the troposphere. They are also the result of unequal heating of the atmosphere. Jet streams circle the planet, mainly from west to east. The strongest jet streams are the polar jets.

describe the difference between a land and sea breeze and what causes each

Ocean water is slower to warm up and cool down than land. So the sea surface is cooler than the land in the daytime. It is also cooler than the land in the summer. The opposite is also true. The water stays warmer than the land during the night and the winter. These differences in heating cause local winds known as land and sea breezes. A land breeze blows from land to sea during the night or in winter. That's when air over the water is warmer than air over the land. The warm air rises. Cool air from the land flows out to take its place. A sea breeze blows from sea to land during the day or in summer. That's when air over the land is warmer than air over the water. The warm air rises. Cool air from over the water flows in to take its place.

how does the atmosphere support life on earth?

Plants need carbon dioxide for photosynthesis. They use sunlight to change carbon dioxide and water into food. The process releases oxygen. Without photosynthesis, there would be very little oxygen in the air. Other living things depend on plants for food. These organisms need the oxygen plants release to get energy out of the food. Even plants need oxygen for this purpose. The atmosphere protects living things from the Sun's most harmful rays. Gases reflect or absorb the strongest rays of sunlight. Gases in the atmosphere surround Earth like a blanket. They keep the temperature in a range that can support life. Water vapor in the atmosphere caused by evaporation, condenses due to changes in atmospheric temperature. This creates clouds and rain, rivers, and streams to help support life through a "water cycle". This water cycle also causes weathering which creates topsoils for plant life. Gases in the atmosphere also support life by transmitting most sounds so communication can take place. Air molecules vibrate and pass the signal along to a recipient. Communication is important for life to avoid danger, alert other animals and mate.

what was the purpose of the clean air act?

Poor air quality started to become a serious problem during the Industrial Revolution. After 1900, motor vehicles added greatly to the problem. By 1970, it was clear that something needed to be done to protect air quality. In the U.S., the Clean Air Act was passed. It limits what can be released into the air. As a result, the air in the U.S. is much cleaner now than it was 50 years ago. But air pollution has not gone away. Vehicles, factories, and power plants still release more than 150 million tons of pollutants into the air each year.

explain the difference between primary and secondary pollutants and give at least 3 examples of each.

Primary pollutants enter the air directly. Some are released by natural processes, like ash from volcanoes. Most are released by human activities. They pour into the air from vehicles and smokestacks. Several of these pollutants are described below: 1. Carbon oxides include carbon monoxide (CO) and carbon dioxide (CO2). Carbon oxides are released when fossil fuels burn. 2. Nitrogen oxides include nitric oxide (NO) and nitrogen dioxide (NO2). Nitrogen oxides form when nitrogen and oxygen combine at high temperatures. This occurs in hot exhausts from vehicles, factories, and power plants. 3. Sulfur oxides include sulfur dioxide (SO2) and sulfur trioxide (SO3). Sulfur oxides are produced when sulfur and oxygen combine. This happens when coal burns. Coal can contain up to 10 percent sulfur. 4. Toxic heavy metals include mercury and lead. Mercury is used in some industrial processes. It is also found in fluorescent light bulbs. Lead was once widely used in gasoline, paint, and pipes. It is still found in some products. 5. Volatile organic compounds (VOCs) are carbon compounds such as methane. VOCs are released in many human activities, such as raising livestock. Livestock wastes produce a lot of methane. 6. Particulates are solid particles. These particles may be ash, dust, or even animal wastes. Many are released when fossil fuels burn. Secondary pollutants form when primary pollutants undergo chemical reactions after they are released. Many occur as part of photochemical smog. This type of smog is seen as a brown haze in the air. Photochemical smog forms when certain pollutants react together in the presence of sunlight. You can see smog hanging in the air over San Francisco. Photochemical smog consists mainly of ozone (O3). The ozone in smog is the same compound as the ozone in the ozone layer,(O3). But ozone in smog is found near the ground. Figure below shows how it forms. When nitrogen oxides and VOCs are heated by the Sun, they lose oxygen atoms. The oxygen atoms combine with molecules of oxygen to form ozone. Smog ozone in the troposphere is harmful to humans and other living things.

describe heat transfer in the atmosphere- conduction, convection & radiation

Radiation is the transfer of energy by waves. Energy can travel as waves through air or empty space. The Sun's energy travels through space by radiation. After sunlight heats the planet's surface, some heat radiates back into the atmosphere. In conduction, heat is transferred from molecule to molecule by contact. Warmer molecules vibrate faster than cooler ones. They bump into the cooler molecules. When they do they transfer some of their energy. Conduction happens mainly in the lower atmosphere. Convection is the transfer of heat by a current. Convection happens in a liquid or a gas. Air near the ground is warmed by heat radiating from Earth's surface. The warm air is less dense, so it rises. As it rises, it cools. The cool air is dense, so it sinks to the surface. This creates a convection current. Convection is the most important way that heat travels in the atmosphere.

describe each layer of the atmosphere

The troposphere is the shortest layer of the atmosphere. It rises to only about 12 kilometers (7 miles) above the surface. Even so, this layer holds 75 percent of all the gas molecules in the atmosphere. That's because the air is densest in this layer. Air in the troposphere is warmer closer to Earth's surface. Warm air is less dense than cool air, so it rises higher in the troposphere. This starts a convection cell. Convection mixes the air in the troposphere. Rising air is also a main cause of weather. All of Earth's weather takes place in the troposphere. Sometimes air doesn't mix in the troposphere. This happens when air is cooler close to the ground than it is above. The cool air is dense, so it stays near the ground. This is called a temperature inversion. An inversion can trap air pollution near the surface. Temperature inversions are more common in the winter. At the top of the troposphere is a thin layer of air called the tropopause. This layer acts as a barrier. It prevents cool air in the troposphere from mixing with warm air in the stratosphere. The stratosphere is the layer above the troposphere. The layer rises to about 50 kilometers (31 miles) above the surface. Air temperature in the stratosphere layer increases with altitude. The stratosphere gets most of its heat from the Sun. Therefore, it's warmer closer to the Sun. The air at the bottom of the stratosphere is cold. The cold air is dense, so it doesn't rise. As a result, there is little mixing of air in this layer. The stratosphere contains a layer of ozone gas. Ozone consists of three oxygen atoms (O3). The ozone layer absorbs high-energy UV radiation. UV radiation splits the ozone molecule. The split creates an oxygen molecule (O2) and an oxygen atom (O). This split releases heat that warms the stratosphere. By absorbing UV radiation, ozone also protects Earth's surface. UV radiation would harm living things without the ozone layer. At the top of the stratosphere is a thin layer called the stratopause. It acts as a boundary between the stratosphere and the mesosphere. The mesosphere is the layer above the stratosphere. It rises to about 85 kilometers (53 miles) above the surface. Temperature decreases with altitude in this layer. There are very few gas molecules in the mesosphere. This means that there is little matter to absorb the Sun's rays and heat the air. Most of the heat that enters the mesosphere comes from the stratosphere below. That's why the mesosphere is warmest at the bottom. Meteors burn as they fall through the mesosphere. The space rocks experience friction with the gas molecules. The friction makes the meteors get very hot. Many meteors burn up completely in the mesosphere. At the top of the mesosphere is the mesopause. Temperatures here are colder than anywhere else in the atmosphere. They are as low as -100° C (-212° F)! Nowhere on Earth's surface is that cold. The thermosphere is the layer above the mesosphere. It rises to 600 kilometers (372 miles) above the surface. The International Space Station orbits Earth in this layer. Temperature increases with altitude in the thermosphere. Surprisingly, it may be higher than 1000° C (1800° F) near the top of this layer! The Sun's energy there is very strong. The molecules absorb the Sun's energy and are heated up. But there are so very few gas molecules, that the air still feels very cold. Molecules in the thermosphere gain or lose electrons. They then become charged particles called ions. Sometimes the ions in the thermosphere glow at night. Storms on the Sun energize the ions and make them light up. In the Northern Hemisphere, the lights are called the northern lights, or aurora borealis. In the Southern Hemisphere, they are called southern lights, or aurora australis. The exosphere is the layer above the thermosphere. This is the top of the atmosphere. The exosphere has no real upper limit; it just gradually merges with outer space. Gas molecules are very far apart in this layer, but they are really hot. Earth's gravity is so weak in the exosphere that gas molecules sometimes just float off into space.

explain the difference between tropospheric ozone and stratospheric ozone

Tropospheric ozone in smog may damage plants. The effects of ozone add up over time. Plants such as trees, which normally live a long time, are most affected. Entire forests may die out if ozone levels are very high. Other plants, including crop plants, may also be damaged by ozone. The ozone in smog is also harmful to human health. Figure below shows the levels of ozone to watch out for. Some people are especially sensitive to ozone. They can be harmed by levels of ozone that would not affect most other people. These people include those with lung or heart problems. Ozone near the ground (tropospheric ozone) harms human health. But the ozone layer in the stratosphere protects us from solar rays. In the 1980s it was learned that there was a hole in the ozone layer. The chief cause is chlorofluorocarbons (CFCs). These are human-made chemicals that contain the element chlorine (Cl). In the past, CFCs were widely used in spray cans, refrigerators, and many other products. CFCs are stable compounds that can remain in the atmosphere for hundreds of years. Once CFCs are in the air, they float up into the stratosphere. Sunlight breaks apart the molecules. This releases their chlorine atoms (Cl). The free chlorine atoms may then combine with oxygen atoms in ozone. This breaks down the ozone molecules into an oxygen molecule and an oxygen atom. One CFC molecule can break down as many as 100,000 ozone molecules in this way! These forms of oxygen do not protect the planet from ultraviolet radiation. As CFCs destroy ozone in the stratosphere, this lets more UV light strike Earth. The UV light causes skin cancer. It also harms plants and phytoplankton.