Altocumulus
Topic: Water in the Atmosphere: Humidity, Condensation, Clouds and Precipitation · NCERT: Class 11, Ch 10 "Water in the Atmosphere"
Meaning
Altocumulus is a middle-level cloud. "Alto" means middle and "cumulo" means heaped. It appears as white or grey rounded masses in layers or patches, often with blue sky between them. Seen on a humid morning, it shows the air is unstable, meaning it rises easily once heated. That is why it can mean thunderstorms later in the day.
Example
On humid pre-monsoon mornings in eastern India, for example over Kolkata, patches of altocumulus may appear early. By afternoon, rising warm air can build them into thunderstorm clouds that bring sudden storms.
Don't confuse with
- Cirrocumulus: a high ice cloud of much smaller, pure white puffs with no grey shading. Altocumulus is lower, with bigger, often shaded masses.
- Stratocumulus: a low cloud with larger, heavier grey lumps or rolls. Altocumulus sits higher, at middle levels.
Related concepts
- Cloud classification by height
- Cirrostratus
- Cirrocumulus
- Altostratus
- Stratocumulus
- Nimbostratus
- Cumulonimbus