Within the troposphere, the temperature decreases with height. A lapse-rate less than the dry adiabatic lapse-rate is common, and so the stratification of the atmosphere is usually stable. In the stable atmosphere the downward flux of heat is resulted by the turbulent motion. But the process of condensation and evaporation is the most important factor in this lowest part of the atmosphere. The libration of latent heat by the process of condensation is compensated with the downward-flux of heat and thus the libration of latent heat by the process of condensation is a important factor determining the normal stratification in the troposphere.