Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. Water vapor is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. Water vapour is lighter than air and triggers convection currents that can lead to clouds. Water vapor is a greenhouse gas along with other gases such as carbon dioxide and methane.