A Fair-Weather Cumulus Cloud Classification Scheme for Mixed-Layer Studies

Abstract

Not all cumulus clouds can vent mixed-layer air into the free atmosphere. Therefore, three subtypes of fair-weather cumulus clouds are identified based on the nature of their interaction with the mixed layer: forced, active and passive clouds. Forced clouds, the visible tracers within the tops of some mixed-layer thermals, are totally embedded within the mixed layer. Active clouds reach above their level of free convection and are responsible for inhibiting mixed-layer growth and for venting pollutants from the mixed layer. Passive clouds are the decaying remnants of formerly active clouds, and are disconnected from the mixed layer. Abstract Not all cumulus clouds can vent mixed-layer air into the free atmosphere. Therefore, three subtypes of fair-weather cumulus clouds are identified based on the nature of their interaction with the mixed layer: forced, active and passive clouds. Forced clouds, the visible tracers within the tops of some mixed-layer thermals, are totally embedded within the mixed layer. Active clouds reach above their level of free convection and are responsible for inhibiting mixed-layer growth and for venting pollutants from the mixed layer. Passive clouds are the decaying remnants of formerly active clouds, and are disconnected from the mixed layer.