GGR217H5 Lecture Notes - Lecture 2: Lapse Rate, Vapor Pressure, Dew Point
Document Summary
Soil moisture precipitation feedback: precipitation recharges local soil water, which in part returns to the atmosphere by evaporation, from which it returns in part to the soil by precipitation. The reinforcing mechanism (positive feedback) may lead to persistence of either wet or dry conditions on a seasonal or multi-year. Heating of the land and of the air directly above it causes the air to ascend, a direct result of a heated pocket of air being less dense then air that surrounds it. This cooling down is simply a consequence of the heat being distributed over a larger column of air. The upward movement of the heated pocket of air continues until, at some greater height, the pocket of air cools down to the temperature of the surrounding air, which then effectively halts a further upward movement of the air. Heating of the sea or wet land surface causes evaporating and now moist air to ascend.
