The troposphere is the layer of the atmosphere closest to the earth. It extends from the ground to approximately 12km above sea level (though this varies with latitude and with the seasons). It contains around 75% of all the air in the atmosphere, and ...
Since the mid-1970s scientists have been concerned about the harmful effects of certain chlorofluorocarbons (CFCs) on the ozone layer. These CFC compounds are relatively inert and nontoxic, and humans found a use for them as cooling agents in refrigera...
