1.
cumulus cloud
One of the ten standard cloud genera: puffy, cotton-like clouds with flat bases and rounded tops, typically forming on fair-weather days by thermal convection in the lower atmosphere.
空に積雲が浮かぶ。
Cumulus clouds float in the sky.
夏の午後は積雲がよく発達する。
Cumulus clouds often develop well on summer afternoons.
積雲は白くて綿のような形をしている。
Cumulus clouds are white and shaped like cotton.
積雲が大きく発達すると、やがて積乱雲になり雷雨をもたらすことがある。
When cumulus clouds develop greatly, they can eventually become cumulonimbus and bring thunderstorms.
Composed of 積 (pile up, accumulate) and 雲 (cloud). One of the ten standard cloud classifications (十種雲形) used in meteorology.
USAGE:
- A technical meteorological term but widely recognized in everyday contexts (weather reports, science textbooks).
- Used as a plain noun; does not take する.
COMMON COLLOCATIONS:
- 積雲が発達する: cumulus clouds develop
- 積雲が浮かぶ: cumulus clouds float (in the sky)
- 夏の積雲: summer cumulus clouds
RELATED TERMS:
- 積乱雲: cumulonimbus — a towering, thundercloud form developed from cumulus
- 層雲: stratus — flat, layered low clouds
- 巻雲: cirrus — wispy high-altitude clouds
- 入道雲: thunderhead (colloquial) — everyday word for a large cumulus/cumulonimbus