The kanji compound word for Japan's annual rainy season — set to commence in early June — is the poetic 梅雨 ("plum rain," baiu/tsuyu), but any resident of the archipelago whose closets have been invaded by noxious green mold during 梅雨 will appreciate why it was originally written 黴雨 ("moldy rain," also pronounced baiu).
The second kanji in 梅雨, 雨 (rain, ame), comprises a horizontal line, representing the heavens, with clouds and four raindrops underneath. The vertical line in 雨 symbolizes "descent from the heavens." The kanji 雨 serves in a dozen general-use characters and always occupies the celestial (top) position. Most rain-component kanji represent meteorological concepts, but there are exceptions.
In ancient, fire-lit China, 電 (DEN) meant "lightning," but now it mostly refers to "electricity." 電 was the first rain-component kanji my bicultural American/Japanese sons analyzed, at my urging, as second-graders. Sean saw a lightning bolt (し) running through a rice field (田) under a rainy sky. Lukas imagined Benjamin Franklin standing in a rainstorm clutching a kite (田) with a tail (し). On a recent family trip to China, we noted the simplified People's Republic of China (PRC) character for "electricity" was missing the rain element, consisting only of Lukas' "kite."