Title: Unit 12 Glossary
Course: BIS 105 Environmental Biology > Section: BIS 105 Environmental Biology

Unit 12 Glossary

Terms

Term | Definitions
air pressure | The force of air pressing on a given area.
altitude | Distance above sea level.
aurora | A spectacular light display that occurs in the ionosphere near the poles; called the <i>aurora borealis</i> or northern lights in the Northern Hemisphere, and the <i>aurora australis</i> or southe ...
Coriolis effect | The tendency of a freely moving object to appear to move right right in the Northern Hemisphere and left in the Southern Hemisphere.
exosphere | The outermost layer of the atmosphere, where gas molecules are extremely far apart and some occasionally escape earth’s gravity and fly off into outer space.
greenhouse gases | Gases that trap heat in the atmosphere; these include water vapor, carbon dioxide, methane and ozone.
high pressure zone | A region where relatively cool, dense air is sinking.
humidity | The amount of water vapor held in the air; usually refers to relative humidity, meaning the amount of water the air holds relative to the total amount it could hold.
inversion | A situation in the troposhere in which warm air lies above cold air.
ionosphere | An ionized layer contained within the thermosphere; the second to the last layer of the atmosphere.
low pressure zone | A region where relatively warm, less dense air is rising.
mesosphere | The layer of the atmosphere between the stratosphere and the thermosphere; temperature decreases with altitude.
noble gases | Gases that usually do not react chemically and have no color, taste, or odor; these are helium, neon, argon, xenon and krypton.
ozone | A molecule made of three oxygen atoms; ozone in the lower atmosphere is a pollutant, but in the upper atmosphere it filters out the sun’s most harmful ultraviolet radiation.
ozone hole | A region around Antarctica in which ozone levels are reduced in springtime, due to the action of ozone-destroying chemicals.
ozone layer | A region of the stratosphere where ozone gas is more highly concentrated.
photochemical smog | This type of air pollution results from a chemical reaction between pollutants in the presence of sunshine.
polar stratospheric clouds | Clouds that form in the stratosphere when it is especially cold; PSCs are necessary for the breakup of CFCs.
stratosphere | The second layer of the atmosphere, where temperature increases with altitude due the presence of ozone.
thermosphere | The second to the last layer of the atmosphere where gases are extremely thinly distributed.
troposphere | The lowermost layer of the atmosphere.
ultraviolet radiation | High energy radiation that comes from the Sun; there are three types of UV radiation: UVA, UVB, and UVC. The shortest wavelength, and therefore the most dangerous, is UVC.
volatile organic compounds (VOCs) | Pollutants that evaporate into the atmosphere from solvents and other humanmade compounds. Some VOCs occur naturally.
water vapor | The gas form of water.
weather | The temporary state of the atmosphere in a region; the weather in a location depends on the air temperature, humidity, precipitation, wind and other features of the atmosphere.