albedo Ability of a surface to reflect light.

CFCs See chlorofluorocarbons. 

Chlorofluorocarbons (CFCs) Organic compounds made up of atoms of carbon, chlorine, and fluorine. An example is Freon-12 (CCl2F2), used as a refrigerant in refrigerators and air conditioners and in making plastics such as Styrofoam. Gaseous CFCs can deplete the ozone layer when they slowly rise into the stratosphere and their chlorine atoms react with ozone molecules.

Freons See chlorofluorocarbons. 

global warming Warming of the earth's atmosphere because of increases in the concentrations of one or more greenhouse gases primarily as a result of human activities. See greenhouse effect, greenhouse gases. 

greenhouse effect Natural effect that releases heat in the atmosphere (troposphere) near the earth's surface. Water vapor, carbon dioxide, ozone, and several other gases in the lower atmosphere (troposphere) absorb some of the infrared radiation (heat) radiated by the earth's surface. This causes their molecules to vibrate and transform the absorbed energy into longer-wavelength infrared radiation (heat) in the troposphere. If the atmospheric concentrations of these greenhouse gases rise and they are not removed by other natural processes, the average temperature of the lower atmosphere will increase gradually. Compare global warming. 

greenhouse gases Gases in the earth's lower atmosphere (troposphere) that cause the greenhouse effect. Examples are carbon dioxide, chlorofluorocarbons, ozone, methane, water vapor, and nitrous oxide. 

mesosphere Third layer of the atmosphere; found above the stratosphere. Compare stratosphere, troposphere. 

ozone depletion Decrease in concentration of ozone (O3) in the stratosphere. See ozone layer. 

ozone layer Layer of gaseous ozone (O3) in the stratosphere that protects life on earth by filtering out most harmful ultraviolet radiation from the sun.