Genre: Information/Explanation

Water vapor is the most potent of the greenhouse gases in Earth's atmosphere , and it 's sort of a unique player among the greenhouse gases . The amount of water vapor in the atmosphere can not , in general , be directly modified by human behavior – it 's set by air temperatures . The warmer the surface , the greater the evaporation rate of water from the surface . As a result , increased evaporation leads to a greater concentration of water vapor in the lower atmosphere capable of absorbing infrared radiation and emitting it downward . Surface-level ozone Johnny Stockshooter – age fotostock / Imagestate The next most significant greenhouse gas is surface , or low-level , ozone ( O 3 ) . Surface O 3 is a result of air pollution ; it must be distinguished from naturally occurring stratospheric O 3 , which has a very different role in the planetary radiation balance . The primary natural source of surface O 3 is the subsidence of stratospheric O 3 from the upper atmosphere toward Earth's surface . In contrast , the primary human-driven source of surface O 3 is in photochemical reactions involving carbon monoxide ( CO ) , such as in smog .