Tropopause

The boundary between the troposphere and stratosphere, characterized by an abrupt change in temperature lapse rate (temperatures decrease with height in the troposphere, but it increases or remains constant with height in the stratosphere).

Tropopause The boundary layer between the troposphere and stratosphere, where an abrupt change in temperature lapse rate usually occurs. It is defined as the lowest level at which the lapse rate decreases to 2 °C km-1 or less, provided that the average lapse rate between this level and all higher levels within 2 km does not exceed 2 °C km-1. Occasionally, a second tropopause may be found if the lapse rate above the first tropopause exceeds 3 °C km-1.

The upper boundary of the troposphere, usually characterized by an abrupt change in lapse rate from positive (decreasing temperature with height) to neutral or negative (temperature constant or increasing with height).

The imaginary boundary layer dividing the stratosphere from the lower part of the atmosphere, the troposphere. The tropopause normally occurs at an altitude of about 7.62km to 13.71km in polar and temperate zones, and at 16.76km in the tropics. (See Stratosphere, Troposphere.)