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Current Category » Agricultural Meteorology

Clouds, It's Types and Their Classification

Cloud can be defined as a mass of tiny water droplets ice crystals OR both condensed on hygroscopic nuclei and suspending in the atmosphere.

Clouds and fogs are composed of water droplets or ice crystals or both of the order of size 20 to 60 microns (0.008-0.024 millimeter).

Lime joining places of equal clouds cover on a map is known as isoneph.

Principles of cloud classification :

The great variety of cloud forms necessitates a classification of weather reporting. The internationally adopted system is based upon (a) The general shape; structure and vertical extend of the clouds and (b) their altitude.
Types of clouds: There are four basic types of clouds:

1. Clrrus (CI):
Meaning “cur” and is recognized by its veil, like fibrous or featery form.  It is the highest type of cloud, ranging from approximately 7-12 km in altitude. (20,000 to 35,000 feet).

2.  Cumulus (Cu):
Meaning “heap”, is the wooly, bundly cloud with rounded top and flat base.  It is the most common in the summer season and in latitudes where high temperature prevail and it always results from convection Its height is variable and depends on relative humidity of the air.

3.   Stratus (St):
It is a sheet type cloud without any form to distinguish it.  It is usually lower than cumulus.

4. Nimbus (Nb):
It is any dark and ragged cloud and from which precipitation occurs.

Classification Of Clouds
Clouds have been classified according to their height and appearance by world Meteorological organization (WHO) into 10 categories.

Cloud family and Height

Name of cloud and abbreviation


Possible weather change

Description and appearance






Family A High clouds 7 to 12 km

1 Cirrus (Ci)

Ice crystals

May Indicate storm showery weather

It is wispy and feathery, sun shines without shadow.  It does not produce precipitations




2. Cirrocumulus (CC)

Ice crystals

Possible storm

Meekerel sky, often fore renners of cyclone, look like sippled sand


3. Cirrostratus(Cs)

Ice crystals

Possible storm

Meekeral sky, often fore runners of cyclone, look like sippled sand.

Family B middle clods 3 3-7 km

4. Altocumulus (As)

Ice & water

Steady rain or snow

Looks like wool peak, sheep bulk clouds.


5. Atmostratus (As)

Water and ice

Impending rain or snow

Fibrous veil or sheet, grey or bluish, produce coronos, usually shadow.

Family C low clouds from ground to km

6. Stratocumulus (Se)


Rain possible

Long parallel rolls, pushed together or broken masses which look soft and grey but with darker parts, air is smooth above but strong updrafts occur below.


7. straus (St)


May produce drizzle

A low uniform layer, resembling fog, but resting not on the ground, chief winter cloud.



Water or Ice

Impending rain or snow

Fibrous veil or sheet, grey, grey or bluish produce coronas, usually

Family D clouds with vertical development from 0.5 to 16 km

9.Cumu-lus (Cu)


Fair weather

Looks like wool pack, dark below due to shadow, may develop into cumulous –Nimbus flat base.


10, Cumulous –Nimbus (Cb)

Ice in upper level and water in lower level.

Violet winds rain, all possible thunderstorm hail lighting possible

Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus, chief precipitation makers.


10 cumulo-Nimbus(Cb)

Ice in upper level and water in lower level

Violet winds rain, all possible thunderstorm hail lighting  possible

Thunder head, towering anvil top, violet up and down drafts, aviators avoid them, develop from cumulus chief precipitation makers.

Current Category » Agricultural Meteorology