Water Vapor Water vapor is the most important natural greenhouse gas. A greenhouse gas traps the infrared radiation that comes from the sun. The trapped infrared radiation warms up the earth. This phenomenon is called the greenhouse effect. Water vapor also redistributes energy in the atmosphere.
Water vapor is removed from the atmosphere during precipitation and returns by evapotranspiration.
The concentration of the water vapor varies in the atmosphere depending on the place and time of year. The concentration of water vapor is greatest over the oceans and tropical rain forest. Carbon Dioxide Carbon dioxide is the fifth most abundant gas in the atmosphere. Carbon dioxide enters the atmosphere during volcanic eruption, biomass and fossil fuel combustion, cement manufacturing and deforestation. Carbon dioxide is removed from the atmosphere during photosynthesis and by dissolving in the oceans.