noun
arcus cloud
A low, horizontal cloud formation associated with thunderstorms; often appears as a shelf or roll cloud.
アーチ雲は、積乱雲の底にできることが多い。
Arcus clouds often form at the base of cumulonimbus clouds.
気象予報士がアーチ雲の接近を伝えた。
The weather forecaster reported the approach of an arcus cloud.