Clouds are made up of millions of tiny water droplets. Clouds are made when quite warm, moist air rises into the sky where it cools down and condenses. Clouds can form in a few minutes or over a number of hours. There are many different types of cloud and looking at them can help you to predict the weather.

The amount of cloud in the sky is measured in eighths (or oktas by meteorologists). Simple observation can be made such as
Clear – no cloud cover
Partly cloudy – less than half cloud cover
Mainly cloudy – more than half cloud cover but with some breaks in the cloud
Overcast – complete cloud cover

Cloud can be measured through a number of observations. Consider whether the cloud is:

HIGH(5,500-14,000 meters)
Includes: Cirrus, cirrocumulus, and cirrostratus
MEDIUM(2,000-7,000 meters)
Includes: Altocumulus, altostratus, and nimbostratus
LOW(below 2,000 meters)
Includes: Stratocumulus, Stratus, Cumulus, and Cumulonimbus
AltitudeNameColourDescriptionWeather
HIGHCirrus

Cirrostratus
White

Whitish
Thin silky and feathery

Fat, smooth transparent sheet
Fair

Worsening
MEDIUMAltocumulus


Altostratus

Nimbostratus
White/grey


Greyish

Dark grey
Layers and waves often separated by blue sky

Thin sheets/layers

Thick sheets
Fair


Rain on way

Continuous rain/snow
LOWStratocumulus


Stratus


Cumulus

Cumulonimbus
Grey/white


Grey


Grey/white

Grey/white
Layers in rounded rolls. No breaks.

Thin sheet blanketing sky

Puffy clouds

Very tall puffy clouds
Dry/dull


Drizzle


Good

Storms. Heavy rain/hail/snow