Standard word for an umbrella used against rain. Contrasts with 日傘 (ひがさ, parasol/sun umbrella).
It looks like rain, so you'd better take an umbrella.
日傘 blocks sunlight while 雨傘 is used to stay dry in the rain, making them opposite-purpose counterparts of the same object.
Standard kanji spelling for 'umbrella'.
Mixed kanji-kana spelling; less common but still used.
Compound of 雨 (あま, rain) + 傘 (かさ, umbrella), with rendaku voicing of かさ to がさ.