積乱雲

1. Origins, structure, and basic meaning

• Structure: 積乱雲 is a meteorological noun read せきらんうん and denotes a cumulonimbus cloud that develops to a great vertical height.
• Basic usage: 積乱雲が成長する describes the cloud developing, while 空にそびえる積乱雲 describes its towering appearance.

2. Common pitfalls and similar expressions

• Cloud type and appearance
  • A cloud is not necessarily a cumulonimbus cloud merely because it looks white or tall. 積乱雲 names a particular type of strongly developed cloud.
• Range of the English equivalents
  • “Cumulonimbus cloud” precisely names the cloud type, while “thundercloud” emphasizes a cloud associated with a thunderstorm. The focus can differ by context.
• 成長 with clouds
  • 雲が成長する describes a cloud developing and increasing in size, not biological growth.