The Contribution of Infrared Cooling to the Vertical Motion Field and Its Implication in Atmospheric Energetics

The validity of the adiabatic assumption used in estimating vertical motion is examined by comparing the relative contributions due to adiabatic processes with the diabatic process of infrared cooling. Radiometersonde data are used to prepare vertical profiles of the adiabatic and infrared components of the vertical motion. These data are first filtered to reduce the effect of random errors. Although the adiabatic component of the vertical motion is usually much larger than the infrared component, the profiles indicate that the infrared component can be important in determining the total vertical motion. A comparison of the contribution of the infrared component in cloudy versus clear sky conditions shows that this component contributes more to downward vertical motion in clear air than in the cloudy situations. The consequences of this systematic variation in estimating energy conversions is discussed. I n view of these results the effect of other diabatic processes is very briefly considered.