The composition of soil affects the climate primarily through the amount of water it retains or which evaporates from it. A soil that contains a large proportion of clay retains more moisture than one that is predominantly sand. The extent to which soil moisture retains affects the humidity and temperature of the air above it. After heavy rain, the soil contains lots of water and modifies microclimate much similar to water bodies like lakes.  Other than mineral composition of soil, the degree of coverage it has will influence moisture and temperature evaporation Bare soil will receive more light and heat than those covered by plants.