Encyclopedia

CAPE is a measure, in joules per kilogram (J/kg), of the energy available to a rising air parcel once it becomes positively buoyant relative to its surroundings. It is the primary thermodynamic index used to estimate how strong thunderstorm updrafts could become on a given day. Forecasters treat it as a standard input to every…

CIN (also written CINH) is a measure, in joules per kilogram (J/kg), of the energy an air parcel must expend to overcome a stable layer in the atmosphere before it can rise freely. That stable layer is sometimes called a “cap.” Where CAPE (Convective Available Potential Energy) measures the energy available once convection starts, CIN…