Page 146 - ภาษาอังกฤษสำหรับสายวิทยาการอุตุนิยมวิทยา

141

6. Dissipating Stage

The dissipating stage begins when downdrafts predominate. When the updraft is too
weak to hold the raindrops, precipitation falls through the upd raft. If the updraft is
strong enough to prevent precipitation from falling through it, the precipitation may
fall just outside the upward current. Whichever happens, the effect of the
precipitation is to increase the density of the air by pulling cooler air downward with
it, and to slow the updraft by the action of falling through it. The updraft will be slowed
and finally reversed so that it becomes a downdraft. The downdraft and precipitation
cool the lower part of the storm cloud and the surface over which it lies. The in-flow
of water vapor to the cloud is stopped and the storm dissipates. When all rain and hail
have fallen from the cloud, the dissipating stage is complete.