CAAP Private Pilot License (PPL) Meteorology Practice Test

The environmental lapse rate is the rate at which the ambient air temperature changes with height in the real atmosphere. It describes the actual temperature profile you’d observe with increasing altitude at a particular place and time, which can vary from day to day and location to location. Typical values are around 6.5°C per kilometer in the standard atmosphere, but the rate can be steeper or shallower, and inversions occur when temperature increases with height. This concept helps explain atmospheric stability: if the environmental lapse rate is steeper than the dry adiabatic lapse rate, the atmosphere tends to be unstable; if it’s shallower, it tends to be stable. Humidity, wind, and pressure change with height are described by other profiles, not the temperature profile.