Definition:
A visible
aggregation of minute water droplets or ice particles in the air above the
ground levels i.e. at the certain elevation is called as the cloud.
There are
two major cloud group based on their forms
1. Strati
form Cloud group
These are
the clouds present in the form of layers
2. Cumuli
form Cloud group
It consist of globular
clouds in the form of cotton balls
The world
meteorological organization gave the international cloud atlas consisting of 10
main cloud families. These families are listed according to their heights into
3 groups.
1. High
Clouds
All high
clouds are called as ‘cirro’ clouds and they are present at elevation of 5 to
13 kms.
These clouds are composed of ice crystals and produce
phenomenon called ‘halo’ and does not give rainfall/precipitations they are of
three types
a. Cirrus
- These are detached clouds in the form of white delicate filaments or narrow binds.
- Sometimes they are in the form of white patches.
b. Cirro
Cumulus
- These are the clouds looks like small flakes or globules consisting of white patchy layers of clouds without shading.
- When these patches are uniformly arranged, it forms a ‘mackerel sky’
c. Cirro
status
These are
the transparent whitish clouds in the form of a fibrous veil with smooth
appearance.
2. Middle
Clouds
All
middle clouds are called as the alto clouds. They are present in the height
ranging from 2 to 7 Kms. They of three types
d. Alto
Cumulus
- It’s a white or grey patchy layer of cloud having dark shading on their under surfaces.
- Sometimes they are found in wavy or parallel bonds where they are referred as sheep or wool packed clouds.
- Often they are composed of super cooled liquid droplets. They may or may not give rainfall
e. Alto
stratus
- They are grayish or bluish cloud layers having fibrous appearance covering most part of the sky.
- The sun is vaguely revealed in the form of spot.
- But the ground shadows are not cast.
- They give out fine drizzle of snow
f. Nimbo
stratus
- It is a grey cloud layer often very dark, thick enough to blot the sun.
- The rain or snow falling from this cloud does not reach the ground and called as virga.
3. Low
Clouds
These are
the clouds present below 2 kms of elevation and there are 4 types of cloud
families are present in this
g. Strato
cumulus
- It is a low cloud layer which is dull grey in colour consisting of large lumpy masses with brighter intersects
h. Stratus
- This is a grey cloud layer.
- The sun is visible and its outline is clearly distinguishable.
- They are also present in the form of raged patches.
i. Cumulus
- These are dense detached clouds with sharp outline developing vertically in the forms of mount or tower like cauliflower.
- The sunlit part is brighter and the base is dark.
- They represent transition to the cumulo nimbus clouds and are present only during day time
j. Cumulo
nimbus
- These are heavy & dense cloud forms having an anvil head.
- These are towering clouds from the ground level to intermediate heights.
- They are associated with heavy rainfall, thunders, lighting.
