Adiabatic lapse rates refer to temperature changes as altitude increases with no heat loss or gain to and from the surrounding environment. Adiabatic lapse rates can be distinguished as dry or moist. Condensation and latent heat release make the Moist Adiabatic Lapse Rate (MALR) slower than the Dry Adiabatic Lapse Rate (DALR). The DALR can have water vapor but not liquid moisture in cloud, droplet, or fog form. If an air parcel is raised by 1000m in height, it will cool by approximately 9.8°c based on the DALR.
In contrast, atmospheric conditions become complicated when moisture is added. The Clausius-Clapeyron relationship suggests that air has a high saturation rate at lower temperatures, given similar moisture amounts. At the dew point, an air parcel will continue to cool, condensing the water vapor into liquid water to make a cloud. As water vapor undergoes condensation, it moves to a low energy state from a high energy state. Energy is not destroyed or created during the phase changes. The excess energy is released in a latent heat form.
The latent heat release distinguishes the MALR from the DALR. After latent heat release during the condensation process, latent heat counteracts adiabatic cooling resulting from the air parcel’s expansion. As a result, the air parcel cannot cool according to the DALR. Instead, it will cool at a much slower pace, commonly known as the MALR. In summary, due to condensation accompanied by latent heat release, the MALR is slower than the DALR. Furthermore, latent heat limits the adiabatic cooling of an air parcel, reducing the cooling rate after the air parcel goes beyond the dew point.