Evapotranspiration is the combination of water evaporated from soil, surface water, etc., and water transpired from the leaves of plants. It’s an incredibly important measure of what’s going on in the hydrologic system. Which is why I love this new map:

US Evapotranspiration, from Sanford and Selnick

From Estimation of Evapotranspiration Across the Conterminous United States Using a Regression With Climate and Land-Cover Data, Sanford and Selnick, Journal of the American Water Resources Association, Volume 49, Issue 1