Common Cloud Types

High Clouds:

Cirrus (Ci), 20 - 40,000

- "Mares' tails"

- Bad weather coming

Cirrostratus (Cs), 20, 000

- Showers or rain soon

Cirrocumulus (Cc), 18 - 20, 000

- "Mackerel skies"

- Unsettled weather

Middle Clouds:

Altostratus (As), 15 - 20, 000

- Rain likely

Altocumulus (Ac), 10, 000

- Sunny periods

Low Clouds:

Stratus (St), 100 - 300

- Drizzle coming

Stratocumulus (Sc), 1,500 - 6,500

- Dry but dull weather

Nimbostratus (Ns), 100 - 3, 000

- Rain imminent

Vertically Developing Clouds:

Cumulus (Cu), 2 - 10, 000

- "Woolpack"

- Sunny spells

Cumulonimbus (Cb), 5 - 50, 000

- "Thunderheads"

- Showers and thunder