- Mass of minute water caused mainly by the adiabatic cooling of air below its dew point
- According to their height, expanse, density and or opaqueness clouds are grouped under four types
- Cirrus clouds are formed at high altitudes (8,000-12,000m). They are made of ice crystals.
- They are thin and detached clouds having a feathery appearance.
- They are always white.
- Hair-like clouds found at high altitudes.
- Cumulus clouds look like cotton wool.
- Formed at a height of 4,000-7,000 m.
- They exist in patches
- Can be seen scattered here and there.
- They have a flat base.
- As their name implies, these are layered clouds
- Covering large portions of the sky.
- These clouds are generally formed due to loss of heat
- The mixing of air masses with different temperatures
- Nimbus clouds are black or dark grey.
- They form at of the earth. Middle or near to the surface
- These are extremely dense and opaque to the rays of the sun.
- Nimbus clouds are shapeless masses of thick vapour
COMBINATION OF THESE FOUR BASIC TYPES
- High clouds — cirrus, cirrostratus, cirrocumulus;
- Middle clouds — altostratus and altocumulus;
- Low clouds — stratocumulus and nimbostratus (long duration rainfall cloud; rain bands in tropical cyclones)
- Clouds with extensive vertical development —cumulus and cumulonimbus (thunderstorm cloud)
- High – Cirrostrat Cirrus Cirrocumulus