The Atmosphere
Movement in the Atmosphere
Atmospheric Stability
Localised Winds
Clouds
Fronts
Visibility and Fog
Aircraft Icing
Thunderstorms
Altimetry
Weather Reports and Forecasts
Practice Exam

Cloud Heights

Clouds are not only described by their shape (cumuliform or stratiform) but also by the altitude the cloud starts at. When it comes to cloud heights, the atmosphere is broken up into three layers – low, middle and high.

Low Level Clouds

Clouds with a base between sea level and roughly 6,500 feet fall into the low level category.

Middle Level Clouds

Clouds with a base between roughly 6,500 feet and 20,000 feet fall into the middle level category.

The prefix ‘alto‘ is used to describe middle level clouds.

High Level Clouds

If the cloud base is higher than about 20,000 feet the cloud falls into the high level category.

The prefix ‘cirro‘ is used to descripe high level clouds.

Note that although some clouds can have tops extending into multiple layers, it is the base of the cloud that determines which category a cloud falls into