Definition
A descriptive term used in cloud naming to indicate that the cloud is producing precipitation, such as rain or snow, that reaches the ground.
Plain English
When you see 'nimbus' in a cloud name, it means the cloud is raining or snowing.
Context Anchor
Seen in cloud classification, especially in names such as nimbostratus and cumulonimbus.
Derivation
From Latin 'nimbus,' meaning 'rain cloud' or 'storm.' The original Latin meaning carries straight into modern aviation use — it still flags a cloud that is actively producing precipitation.
Why Pilots Care
Nimbus clouds signal active precipitation, which can reduce visibility, create icing hazards, and affect flight planning.
Intuition Check
Do not treat nimbus as a cloud shape by itself. It is mainly a word element that tells you the cloud is connected with precipitation.
Example Sentence 1
The forecast showed nimbostratus over the route, so the pilot expected steady rain and lower ceilings.
Example Sentence 2
Pilots avoid areas with cumulonimbus because the nimbus component brings thunderstorms and turbulence.