Atmospheric Science![Figure][1] In the United States, soil moisture in the east or west has opposite effects on future rainfall. PHOTO: GEORGE RANALLI/SCIENCE SOURCE Soil moisture, which is controlled in part by past rainfall, can affect the probability of future rainfall over large areas. This is because the water contained in soils helps determine how sunlight is converted into latent heat (evaporation) and sensible heat (which increases overlying air temperatures). Tuttle and Salvucci used data collected for the contiguous United States over 10 years to study this relationship. The feedback between soil moisture and rainfall is generally positive in the western United States but negative in the east. This regional dependence could be a function of large-scale differences in aridity. Science , this issue p. [825][2] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aaa7185