Environmental Temperature Lapse Rates
The rate of change in temperature with height between mandatory
pressure levels (850-700 mb and 700-500 mb), or fixed layers above ground level (Sfc-3km and 3-6km).
A dry adiabatic temperature profile will have lapse rates near 9.6 C/km, while the moist adiabatic lapse
rate is near 6 C/km. Lapse rates greater than 9.6 C/km are said to be "superadiabatic" or "absolutely
unstable", lapse rates between dry and moist adiabatic are "conditionally unstable", and lapse rates less
than moist adiabatic are "absolutely stable".
Conditionally unstable lapse rates in the mid troposphere are necessary for deep convection, while low-level
lapse rates will often become superadiabatic during the afternoon near the ground. If the lapse rates are
"steep" from the surface to 3 km AGL, then convective inhibition is usually weak and thunderstorm development
could occur (given sufficient moisture).