temperature lapse rate in atmospheric chemistry

The rate of change of temperature with altitude ( $d T d z$ ). The rate of temperature decrease with increase in altitude which is expected to occur in an unperturbed dry air mass is $9.8 × 10 3 °C min −1$ . 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 $6.5 × 10 3 °C min −1$ . The lapse rate has a negative value within an inversion layer.

Source:

PAC, 1990, 62, 2167 (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2199