Downdraft Strength: Importance and Contributions - 1
Downdraft strength and the resulting surface cold pool determine the strength of convective winds and the cold pool's ability to trigger new cells. The primary contributors to downdraft strength include precipitation loading and evaporation.
Precipitation loading effectively adds weight to the rising air parcel. The magnitude of precipitation loading depends both on the amount of moisture in the parcel and on the strength of the updraft, which initially suspends the precipitation.
Evaporation makes the falling air parcel colder than the surrounding air. This makes the air more dense and consequently strengthens the downdraft. The effects of evaporation depend on the amount of precipitation that can be evaporated, the dryness of the air it evaporates into, and the precipitation type.