Atmospheric Vortex Engine



ABSTRACT

Entrainment and detrainment required to explain updraft properties and work dissipation.

© Tellus A
A one-dimensional lateral entrainment thermodynamic model is used to determine updraft virtual temperature excess, updraft velocity, and other updraft properties from sounding data. The unique feature of the model is that fractional entrainment and detrainment are both functions of the virtual temperature excess of the updraft and independent of updraft mass or diameter. The updraft temperature and composition are rigorously determined before updraft velocity is considered. The entrainment and detrainment functions allow the flows in and out of the updraft to vary in a physically realistic way and are used from the base of the sounding to cloud top.
The calculated updraft properties are reasonable and they reveal how work of buoyancy is dissipated. The model correctly limits the growth of cumulus under conditions of dry air aloft. The model predicts higher intensity for continental than for oceanic updrafts. High humidity at the bottom of the atmosphere in oceanic areas decreases the intensity of the updrafts because it lowers the condensation level, the level at which evaporative cooling comes into play. Low humidity aloft decreases the intensity of the updrafts because it enhances evaporative cooling.

[Link to Entrainment and Detrainment Paper]