Clouds- Definition and Classification

Cloud is a visible, Dense mass of suspended water droplets or ice crystals, or Particles suspended in the air. Clouds are formed when air is forced to rise at a front, over mountains, or because of convection.

The formation of cloud is a result of saturation of air when it is cooled to its dew point, or when it gains sufficient moisture from an adjacent source to raise the dew point to the ambient temperature. (You can read the water cycle).

Types of Clouds: Luke Howard (Englishman) first classified clouds in 1803.

Classification of clouds – Luke Howard

Stratus – The Cloud lying in a level Sheet. Cumulus – The Cloud having a flat base and rounded tops and being lumpy in appearance Cirrus – The cloud having a fibrous or feathery appearance.


There are 10 basic types of Clouds according to the International standard under the World Meteorological Organization as published in The International Cloud Atlas.

High Clouds- (above 7000 m)

Cirrus (Ci)-

  • These clouds characterized by thin, wispy strands.
  • Its name is from the Latin word cirrus, meaning a ringlet or curling lock of hair detached clouds, in the form of white patches or narrow bands.
  • These types of clouds have a fibrous hair-like appearance or silky sheen or both.

Cirrocumulus (Cc)-

  • These clouds are thin, white patches, sheets, or layers of clouds without shading composed of very small elements in the form of grains, etc.
  • These may be merged, or separate, less or more regularly arranged

Cirrostratus (Cs)-

  • these are transparent, whitish cloud veil of fibrous or smooth appearance totally or partially covers the sky or mackerel sky,
  • These clouds generally producing halo phenomena.

Middle Cloud-(2000 to 7000m)

Altocumulus (Ac)

  • These clouds characterized by globular masses or rolls in layers or patches.
  • The individual elements being larger and darker than those of cirrocumulus and smaller than those of stratocumulus.
  • They are usually regularly arranged, small elements usually have apparent width between 1 and 5 degrees.

Altostratus (As)

  • These are Greyish or Bluish cloud sheet or layer of striated, fibrous, or uniform appearance, totally or partly covering the sky
  • These are thin and reveals the sun at least vaguely.
  • The sun is dimly visible; the altostratus clouds do not show halo phenomena.

Low Clouds (below 2000m)

Nimbostratus (Ns)

  • The clouds are of grey colored, dark and the appearance is rendered diffuse by more or less continually falling rain or snow, in most cases reaches the ground
  • These are low-ragged clouds that frequently occur below the layer with which they may or may not merge.

Stratocumulus (Sc)

  • These are grey or whitish, or both patch sheets or layers of clouds with dark parts, composed of tessellations, rounded masses, rolls, etc.
  • These are non-fibrous (except- virga), and may or may not be merged.

Stratus (St)

  • A Grey cloud layer with a uniform base, ice prisms, snow grains have shown.
  • The outline of the cloud is clearly discernible when the sun is visible through it.
  • It does not produce halo phenomena, (possible at very low temperature)
  • Sometimes the cloud appears as ragged patches.


  • These clouds are generally dense and having sharp outlines, developing vertically in the form of rising mounds, domes, or towers.
  • The sunlit part of the cloud is mostly white
  • The bases are relatively dark and nearly horizontal. Sometimes cumulus is ragged.

Cumulonimbus (Cb)

  • These clouds are heavy and dense, with a vertical extent, in the form of mountain huge towers.
  • Part of the upper portion is usually smooth or fibrous of striated and flattened, it spreads in the anvil or plume shape.
  • These clouds give torrential rainfall.
  • Lighting and thunder are common features of these clouds.

Clouds- Definition and Classification


You can also read:

Spread Your Love


List of Important Local Winds - PCSSTUDIES - Geography · March 29, 2022 at 11:25 am

[…] Clouds- Definition and Classification […]

  • Atmosphere: Composition and Structure - PCSSTUDIES - Geography · November 6, 2022 at 5:10 pm

    […] contains approximately 90% of the total mass of the atmosphere and the bulk of all water vapour, clouds, weather, and air […]

  • Leave a Reply