the temperature at which the vapor pressure of a liquid is equal to 1 atm
Vapor pressure As a general trend, vapor pressures of liquids at ambient temperatures increase with decreasing boiling points. This is illustrated in the vapor pressure chart (see right) that shows graphs of the vapor pressures versus temperatures for a variety of liquids.[6] At the normal boiling point of a liquid, the vapor pressure is equal to the standard atmospheric pressure defined as 1 atmosphere[7] (760 Torr or 101 325 kPa).
Water vapor Water vapor, water vapour or aqueous vapor is the gaseous phase of water. It 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. Unlike other forms of water, water vapor is invisible.[4] Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is less dense than air and triggers convection currents that can lead to clouds.