moisture index A term based on the computation of an annual moisture budget by C. W. Thornthwaite (1955), and calculated from the aridity and humidity indices, as I_m = 100 × (S − D)/PE, where I_m is the moisture index, S is the water surplus in months when precipitation exceeds evapotranspiration, D is the water deficit in months when evapotranspiration exceeds precipitation, and PE is the potential evaporation.

moisture index The term used instead of ‘moisture budget’, e.g. by C. W. Thornthwaite (1955), and calculated from the aridity and humidity indices, as I_m = 100 × (S − D)/PE, where I_m is the moisture index, S is the water surplus, D is the water deficit, and PE is the potential evapotranspiration.

moisture index The term used instead of ‘moisture budget’ (e.g. by C. W. Thornthwaite (1955)), and calculated from the aridity and humidity indices, as I_m = 100 × (S−D)/PE, where I_m is the moisture index, S is the water surplus, D is the water deficit, and PE is the potential evapotranspiration.