Calculation of Airflow over an Isolated Heat Source with Application to the Dynamics of V-Shaped Clouds

Abstract

The stably stratified airflow over a three-dimensional elevated heat source is investigated using the linearized equations of motion. A low-level upward motion can be produced for airflow over a prescribed, isolated heat source for a wide variety of mean wind speeds. Above the heating layer, a V-shaped region of upward displacement is formed by the action of the mean wind on the upward propagating waves. The horizontal pattern of the heat source is important in determining the formation of the V-shaped region of upward displacement A high-pressure region is produced in the vicinity of the heat source at the top of the heating layer. The response of a hydrostatic airflow to a transient heating is a V-shaped region of upward displacement with an embedded region of downward displacement above the heated layer. The whole system advects downstream with a slower speed than the mean wind and eventually disperses. A region of strong divergence is associated with the region of upward displacement above the heated layer. In relation to the thunderstorm generated V-shaped clouds, the cold (warm) can be explained by the adiabatic cooling (warming) associated with the upward (downward) displacement. In addition, the upwind displacement of the cold area in the upper level may be explained as a gravity wave type phenomenon.