Clouds are grouped based on two main factors: their height above the ground and their appearance (texture). This system of classification was first proposed by Luke Howard in 1802 and is still largely used today.
There are three main altitude classes for clouds:
- Low clouds: These clouds have bases below 2,000 meters (6,500 feet).
- Mid-level clouds: These clouds have bases between 2,000 and 7,000 meters (6,500 and 23,000 feet).
- High clouds: These clouds have bases above 7,000 meters (23,000 feet).
Within each altitude class, clouds are further classified based on their appearance. The following cloud roots and translations summarize the components of this classification system:
- Cirro-: curl of hair, high
- Alto-: mid
- Strato-: layer
- Nimbo-: rain, precipitation
- Cumulo-: heap
For example, cirrus clouds are high clouds with a wispy, feathery appearance, while cumulus clouds are low clouds with a puffy, cotton-like appearance.
There are 10 main groups, or genera, of clouds. Each cloud belongs to one, and only one, genus. These genera are further divided into species, varieties, and supplementary features, allowing for even more detailed cloud classification.
