Thin, wispy high-altitude clouds made of ice crystals. Often indicate fair weather but can signal an approaching warm front.
basicWhat is Cirrus Clouds?
Cirrus clouds form above 6,000 metres where temperatures are below -40°C, so they are composed entirely of ice crystals. They appear as thin white streaks or curls across the sky. While cirrus themselves do not produce precipitation, an increasing sheet of cirrus (cirrostratus) often precedes a warm front by 12-24 hours, making them useful for weather prediction.
Key points
- Thin, wispy high-altitude clouds made of ice crystals. Often indicate fair weather but can signal an approaching warm front.
- Category: basic
Related terms
See also: cirrus is connected to other weather concepts. Browse the full glossary for related definitions.