Types of Clouds — A Complete Visual Guide

The 10 Main Cloud Types

Clouds are classified by their altitude and shape. The system was invented by Luke Howard in 1803 and remains essentially unchanged.

High Clouds (6,000m+)

• Cirrus — Thin, wispy streaks made entirely of ice crystals. Usually indicate fair weather but can signal a warm front approaching within 24 hours.
• Cirrocumulus — Small, high puffs arranged in rippled patterns. Relatively rare and indicate atmospheric instability.
• Cirrostratus — A thin, translucent sheet that often produces a halo around the sun or moon. Usually means rain within 12-24 hours.

Mid-Level Clouds (2,000-6,000m)

• Altostratus — Grey or blue-grey sheet covering the sky. The sun appears as if behind frosted glass. Light rain or snow often follows.
• Altocumulus — White or grey puffs in layers or rows. On a warm, humid morning, they can signal afternoon thunderstorms.

Low Clouds (below 2,000m)

• Stratus — Flat, featureless grey layer. Produces drizzle or light rain. The classic overcast sky.
• Stratocumulus — Lumpy grey or white masses in rolls or patches. Common worldwide; usually no significant rain.
• Nimbostratus — Thick, dark, rain-bearing layer. Produces steady, prolonged rain or snow.

Vertical Development Clouds

• Cumulus — Puffy white cotton-ball clouds. Small cumulus ("fair-weather cumulus") indicate pleasant conditions. Large, tall cumulus can develop into storms.
• Cumulonimbus — The king of clouds. Towering up to 15,000m with an anvil-shaped top. Produces thunderstorms, heavy rain, hail, lightning, and sometimes tornadoes.

Quick Identification Tips

• Flat and layered = "stratus" family
• Puffy and heaped = "cumulus" family
• "Alto" prefix = mid-level
• "Cirro" prefix = high-level
• "Nimbo" or "nimbus" = rain-producing

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Look up at the sky and check conditions on Weather Tomorrow.