temperature lapse rate

in atmospheric chemistry
The rate of change of temperature with altitude (dT/dz). The rate of temperature decrease with increase in altitude which is expected to occur in an unperturbed dry air mass is 9.8 x 10E3°C min-1. This is called the dry adiabatic lapse rate. The lapse rate is taken as positive when temperature decreases with increasing height. For air saturated with H2O, the lapse rate is less because of the release of the latent heat of water as it condenses. The average tropospheric lapse rate is about 6.5 x 10E3°C min-1. The lapse rate has a negative value within an inversion layer.
PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2199 (https://doi.org/10.1351/pac199062112167)