The hardest part of a student’s pilot flight is maintaining the required clearance from the clouds during his private pilot license. Clouds have always been a threat to non-experienced pilots and have caused a considerable number of aviation accidents and incidents over the years due to the unfamiliarity of the pilots with different clouds and their effects.
Clouds and their effects are taught to student pilots in most flight academies in great details and are also witnessed by student pilots on a daily basis while conducting training flights.
Clouds are collections of water droplets, ice crystals or a mixture of both and they provide rough indications of:
The Average lifetime of traditional clouds that do not lead to a thunderstorm is 15-20 minutes and it ends as either fallen precipitation (rain) or evaporation into a higher level to form another cloud.
Clouds can be sorted by height or characteristics and behavior and but during flight training, student pilots are required to learn clouds sorted by first the specific air and precipitation characteristics then the height in which each type of cloud exists and that is what will be discussed in this article.
|Cloud Classification||State of Stability||Composition|
|Cirriform||Unstable/Stable||Ice crystals only|
|Cumuliform||Unstable||Water droplets and/or ice crystals|
|Stratiform||Stable||Water droplets and/or ice crystals|
These clouds form in stable air and can be further subdivided into categories according to the height bands in which they are found. Hence there are three further subcategories as follows:
|Low level clouds (surface to 6500ft)||Medium level clouds (6500 ft to 23,000ft)||High level clouds(16,500ft to 45,000ft)|
Notice that the medium level and the high level bands overlap. This happens because in the summer the medium level clouds can extend up to 23,000 feet, and in the winter the high level clouds can come as low as 16,500 feet.
Clouds of Great Vertical Extension
These form in unstable air and air not restricted to a particular height band like the layer clouds.
|Cumulus||Surface to 25,000 ft|
|Cumulonimbus||Surface to tropopause|
|Nimbostratus||Surface to 15,000 ft|
A nimbostratus cloud can be a low cloud or a cloud with vertical extension because when there is strong lifting, nimbostratus can behave like a heap cloud and extend through several height bands
Cumulonimbus clouds are the most dangerous types of clouds, extending from the surface to the tropopause which makes it hard for most pilots to clear the clouds by climbing on top of the cloud. This type of cloud is associated with thunderstorms and hailstorms. During a thunderstorm, a downdraught of more than 8,000 feet can be experienced which in the past has led to several aircraft accidents.
Figure 01 summarizes the different types of clouds and the height they are usually found at along with an accurate illustration of what they look like in general.