makes a large contribution to the greenhouse effect Human activities add and subtract water vapor to and from the atmosphere, but these amounts are insignificant compared to the water moved by natural processes Climate change effects of water vapor are difficult to quantify or model because it can both warm or cool the atmosphere
Water in gaseous form It is one of the most import constituents of the atmosphere Due to its molecular content, air containing water vapor is lighter than dry air This contributes to the reason why moist air has a tendency to rise
Water present in the atmosphere in gaseous form; the source of all forms of condensation and precipitation Water vapor, clouds, and carbon dioxide are the main atmospheric components in the exchange of terrestrial radiation in the troposphere, serving as a regulator of planetary temperatures via the greenhouse effect Approximately 50 percent of the atmosphere's moisture lies within about 1 84 km of the earth's surface, and only a minute fraction of the total occurs above the tropopause (Source: Carbon Dioxide Information Analysis Center, 1990)
Water in the form of gas Water exists in three phases at the Earth's surface depending on temperature: liquid water, water vapor, and frozen water or ice
Most abundant GHG Anthropogenic activities are not significantly increasing its concentration, but warming leads to a positive water vapor feedback The concentration of water vapor regulates the temperature of the planet, in part, because of its relationship with the atmosphere and the water cycle
The most abundant greenhouse gas, it is the water present in the atmosphere in gaseous form Water vapor is an important part of the natural greenhouse effect While humans are not significantly increasing its concentration, it contributes to the enhanced greenhouse effect because the warming influence of greenhouse gases leads to a positive water vapor feedback In addition to its role as a natural greenhouse gas, water vapor plays an important role in regulating the temperature of the planet because clouds form when excess water vapor in the atmosphere condenses to form ice and water droplets and precipitation