Clouds exist in three layers in the lower atmosphere; therefore, with four types of clouds and three layers, there are up to twelve major cloud types that have evolved from Luke Howard's pioneering work:

Heaps: Cumulus family clouds:

• Fair weather cumulus
• Swelling cumulus
• Cumulus congestus

Layers: Stratus family clouds:

• Altostratus
• Cirrostratus

Layered Heaps clouds:

• Stratocumulus
• Altocumulus
• Cirrocumulus

Precipitating clouds:

• Cumulonimbus
• Cirrus
• Nimbostratus