Cirrus

• High level
• Wispy/feathery;
• Long and thin;
• Formed of ice crystals

Cumulonimbus Clouds

• Tall/great vertical extent
• Flat top/cauliflower top
• Anvil/wide top
• Dark/black/grey
• Flat base
• Low base
• Thunder/lightning/hail

Cumulus

• Middle level
• Heaped / Fluffy / Cotton Wool
• White;
• Flat base;
• Broken up/discontinuous, etc.
• Dense / Thick

Stratus

• Low level
• Complete cover / fills most of sky / close to each other / sunlight can't get through;
• Grey
• Likely to bring rain/carry lots of moisture/rain clouds, etc.
• Uniform