Determining Stability » Lapse Rates Autoconvective Lapse Rates

There are superadiabatic lapse rates where the temperature decrease with altitude is so great that the density of the air is either constant or increases with altitude. The density of air is constant with height when the lapse rate equals 34.2°C per km. This is known as the autoconvective lapse rate or autoconvection gradient. When this lapse rate is exceeded, the denser air above will spontaneously sink in the less dense air below. This spontaneous overturning of the atmosphere is called autoconvection because the self-convection of air starts without any external impulse. Autoconvection usually occurs with instances of strong surface heating and is confined to a few meters above the earth's surface.