Subsequently, the role of soil moisture in the development of ABL clouds is explored via model simulations, analytical development, and with observational (Cabauw) data in terms of a relative humidity (RH) tendency equation at the ABL top which involves a number of land-atmosphere interactions. It is shown that the effect of soil moisture is to increase ABL-top RH tendency and thus potential for ABL cloud formation (confirming intuition), but only if the stability above the ABL is not too weak (and given sufficient initial RH in the ABL and air above the ABL that is not too dry). Alternately, for weak stability above the ABL, drier soils yield a greater ABL-top RH tendency and thus potential for ABL cloud formation (somewhat counter-intuitive), where in this case soil moisture acts to limit the increase of ABL-top RH, and that the largest values of ABL-top RH tendency are achieved not over moist soils, but rather over dry soils.
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