Clouds

A cloud is a visible collection of tiny water droplets or ice crystals suspended in the air, formed when warm, moist air rises, cools, and condenses. Clouds give us important clues about what’s happening in the atmosphere and what weather may be on the way.

Meteorologists group clouds into four main types:

• Cirrus clouds are thin, wispy, and white, made of ice crystals high in the sky. When scattered and present in small amounts in a clear sky, cirrus clouds usually point to stable, pleasant weather conditions.
• Cumulus clouds are bright and fluffy, often forming recognizable shapes. When small and scattered, they are usually a sign of stable weather.
• Stratus clouds are low, gray, featureless clouds that appear as a flat, uniform sheet covering the sky. They are indicative of stable, overcast weather that may bring light, steady precipitation.
• Nimbus dark dense clouds associated with rain or snow – if you see them, precipitation is likely.

Combined, these main cloud types create about ten different cloud forms. Clouds also form at different heights in the atmosphere, creating layers overhead. And if you see fog around you, you’re actually standing inside a cloud – one that has formed right at ground level!

Read more about clouds from the National Weather Service.