What is the standard average environmental lapse rate in Earth’s troposphere?

The standard average environmental lapse rate in Earth’s troposphere is 6.5 °C per kilometre of altitude.

This value describes the average decrease in temperature with height in the International Standard Atmosphere. It is not a universal rule for every location or moment: actual atmospheric temperature profiles vary with humidity, sunlight, clouds, season, and weather systems.

The figure differs from the dry adiabatic lapse rate, which is about 9.8 °C per kilometre, and the moist adiabatic lapse rate, which is usually lower because condensing water vapor releases latent heat. These adiabatic rates describe air parcels moving vertically, whereas the environmental lapse rate describes the surrounding atmosphere.

The troposphere contains most atmospheric water vapor and nearly all ordinary weather. Its temperature generally falls with height until the tropopause, although inversions can temporarily make temperature increase upward near the surface.