Explain why: a) in hot weather, water is kept in porous earthen vessels to cool water; b) on a hot summer day, after swimming, you can feel the coolness; c) heat usually subsides after rain.
a) water seeps through the pores and wets the outer surface of the vessel, as a result of which the surface area of the liquid increases; b) water evaporates from the surface of the skin, cooling it; c) water heats up and evaporates, absorbing heat from the environment.
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