Water in Atmosphere- 3 | Geography for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
 
WATER IN THE ATMOSPHERE - 3 
CLOUDS  
Cloud is a mass of minute water droplets or tiny crystals of ice 
formed by the condensation of the water vapour in free air at 
considerable elevations. 
It simply means condensation takes place for clouds to form and 
water vapour is converted into water or ice particles.  
Clouds are visible accumulations of tiny water droplets or ice 
crystals in the Earth’s atmosphere. Clouds differ greatly in size, 
shape, and color. They can appear thin and wispy, or bulky and 
lumpy. 
 
Clouds usually appear white because the tiny water droplets 
inside them are tightly packed, reflecting most of the sunlight 
that hits them. White is how our eyes perceive all wavelengths of 
sunlight mixed together.  
 
When it’s about to rain, clouds darken because the water vapor 
is clumping together into raindrops, leaving larger spaces 
between drops of water. Less light is reflected. The rain cloud 
appears black or gray. 
 
NOTE: 
HYGROSCOPIC NUCLEI 
 
In order for cloud droplets to form it also necessary that microscopic 
particles of dust or smoke with a high affinity for water (hygroscopic 
particles) are present in as and serve as condensation nuclei .In the 
Page 2


 
 
WATER IN THE ATMOSPHERE - 3 
CLOUDS  
Cloud is a mass of minute water droplets or tiny crystals of ice 
formed by the condensation of the water vapour in free air at 
considerable elevations. 
It simply means condensation takes place for clouds to form and 
water vapour is converted into water or ice particles.  
Clouds are visible accumulations of tiny water droplets or ice 
crystals in the Earth’s atmosphere. Clouds differ greatly in size, 
shape, and color. They can appear thin and wispy, or bulky and 
lumpy. 
 
Clouds usually appear white because the tiny water droplets 
inside them are tightly packed, reflecting most of the sunlight 
that hits them. White is how our eyes perceive all wavelengths of 
sunlight mixed together.  
 
When it’s about to rain, clouds darken because the water vapor 
is clumping together into raindrops, leaving larger spaces 
between drops of water. Less light is reflected. The rain cloud 
appears black or gray. 
 
NOTE: 
HYGROSCOPIC NUCLEI 
 
In order for cloud droplets to form it also necessary that microscopic 
particles of dust or smoke with a high affinity for water (hygroscopic 
particles) are present in as and serve as condensation nuclei .In the 
 
 
absence of hygroscope particles in the atmosphere condensation 
becomes difficult . 
 
SUPER COOLED MOISTURE 
Water vapour in the air fails to condense sometimes due to lack of 
hygroscopic particles or any other cause in spite of the as parcel having 
been cooled below the dew point is caged super-cooled moisture. This 
phenomenon is rare and generally confined to the upper parts of the 
troposphere.  
 
 
CLOUD CONDENSATION NUCLEI 
Cloud condensation nuclei or CCNs (also known as cloud seeds) are 
small particles typically 0.2 µm, or 1/100th the size of a cloud droplet  on 
which water vapor condenses. Water requires a non-gaseous surface to 
make the transition from a vapour to a liquid; this process is called 
condensation. In the atmosphere, this surface presents itself as tiny solid 
or liquid particles called CCNs. When no CCNs are present, water 
vapour can be supercooled at about -13°C (8°F) for 5–6 hours before 
droplets spontaneously form . 
 
CLOUD SEEDING 
The concept of cloud condensation nuclei is used in cloud seeding, that 
tries to encourage rainfall by seeding the air with condensation 
nuclei. 
Cloud seeding is a type of weather modification that aims to change 
the amount or type of precipitation that falls from clouds by 
dispersing substances into the air that serve as cloud condensation or 
ice nuclei, which alter the microphysical processes within the cloud.  
 
Page 3


 
 
WATER IN THE ATMOSPHERE - 3 
CLOUDS  
Cloud is a mass of minute water droplets or tiny crystals of ice 
formed by the condensation of the water vapour in free air at 
considerable elevations. 
It simply means condensation takes place for clouds to form and 
water vapour is converted into water or ice particles.  
Clouds are visible accumulations of tiny water droplets or ice 
crystals in the Earth’s atmosphere. Clouds differ greatly in size, 
shape, and color. They can appear thin and wispy, or bulky and 
lumpy. 
 
Clouds usually appear white because the tiny water droplets 
inside them are tightly packed, reflecting most of the sunlight 
that hits them. White is how our eyes perceive all wavelengths of 
sunlight mixed together.  
 
When it’s about to rain, clouds darken because the water vapor 
is clumping together into raindrops, leaving larger spaces 
between drops of water. Less light is reflected. The rain cloud 
appears black or gray. 
 
NOTE: 
HYGROSCOPIC NUCLEI 
 
In order for cloud droplets to form it also necessary that microscopic 
particles of dust or smoke with a high affinity for water (hygroscopic 
particles) are present in as and serve as condensation nuclei .In the 
 
 
absence of hygroscope particles in the atmosphere condensation 
becomes difficult . 
 
SUPER COOLED MOISTURE 
Water vapour in the air fails to condense sometimes due to lack of 
hygroscopic particles or any other cause in spite of the as parcel having 
been cooled below the dew point is caged super-cooled moisture. This 
phenomenon is rare and generally confined to the upper parts of the 
troposphere.  
 
 
CLOUD CONDENSATION NUCLEI 
Cloud condensation nuclei or CCNs (also known as cloud seeds) are 
small particles typically 0.2 µm, or 1/100th the size of a cloud droplet  on 
which water vapor condenses. Water requires a non-gaseous surface to 
make the transition from a vapour to a liquid; this process is called 
condensation. In the atmosphere, this surface presents itself as tiny solid 
or liquid particles called CCNs. When no CCNs are present, water 
vapour can be supercooled at about -13°C (8°F) for 5–6 hours before 
droplets spontaneously form . 
 
CLOUD SEEDING 
The concept of cloud condensation nuclei is used in cloud seeding, that 
tries to encourage rainfall by seeding the air with condensation 
nuclei. 
Cloud seeding is a type of weather modification that aims to change 
the amount or type of precipitation that falls from clouds by 
dispersing substances into the air that serve as cloud condensation or 
ice nuclei, which alter the microphysical processes within the cloud.  
 
 
 
The usual intent is to increase precipitation (rain or snow) 
 
 
 
PLEASE NOTE: 
As the clouds are formed at some height over the surface of the earth, 
they take various shapes. 
 
TYPES OF CLOUDS  
Clouds are of different types and they can be classified on the  basis of their 
?  Form  
? Altitude. 
ON THE BASIS OF FORM CLOUDS ARE KNOWN AS 
1) STRATIFORM CLOUDS  
 layered clouds  
2) CUMULIFORM CLOUDS   
massive clouds  
ON THE BASIS OF ALTITUDE CLOUDS ARE CALLED  
1. CIRRUS (HIGHEST CLOUDS)  
 2. ALTO (MEDIUM HEIGHT)  
3 . STRATO (LOW-LEVEL CLOUDS)  
 
Page 4


 
 
WATER IN THE ATMOSPHERE - 3 
CLOUDS  
Cloud is a mass of minute water droplets or tiny crystals of ice 
formed by the condensation of the water vapour in free air at 
considerable elevations. 
It simply means condensation takes place for clouds to form and 
water vapour is converted into water or ice particles.  
Clouds are visible accumulations of tiny water droplets or ice 
crystals in the Earth’s atmosphere. Clouds differ greatly in size, 
shape, and color. They can appear thin and wispy, or bulky and 
lumpy. 
 
Clouds usually appear white because the tiny water droplets 
inside them are tightly packed, reflecting most of the sunlight 
that hits them. White is how our eyes perceive all wavelengths of 
sunlight mixed together.  
 
When it’s about to rain, clouds darken because the water vapor 
is clumping together into raindrops, leaving larger spaces 
between drops of water. Less light is reflected. The rain cloud 
appears black or gray. 
 
NOTE: 
HYGROSCOPIC NUCLEI 
 
In order for cloud droplets to form it also necessary that microscopic 
particles of dust or smoke with a high affinity for water (hygroscopic 
particles) are present in as and serve as condensation nuclei .In the 
 
 
absence of hygroscope particles in the atmosphere condensation 
becomes difficult . 
 
SUPER COOLED MOISTURE 
Water vapour in the air fails to condense sometimes due to lack of 
hygroscopic particles or any other cause in spite of the as parcel having 
been cooled below the dew point is caged super-cooled moisture. This 
phenomenon is rare and generally confined to the upper parts of the 
troposphere.  
 
 
CLOUD CONDENSATION NUCLEI 
Cloud condensation nuclei or CCNs (also known as cloud seeds) are 
small particles typically 0.2 µm, or 1/100th the size of a cloud droplet  on 
which water vapor condenses. Water requires a non-gaseous surface to 
make the transition from a vapour to a liquid; this process is called 
condensation. In the atmosphere, this surface presents itself as tiny solid 
or liquid particles called CCNs. When no CCNs are present, water 
vapour can be supercooled at about -13°C (8°F) for 5–6 hours before 
droplets spontaneously form . 
 
CLOUD SEEDING 
The concept of cloud condensation nuclei is used in cloud seeding, that 
tries to encourage rainfall by seeding the air with condensation 
nuclei. 
Cloud seeding is a type of weather modification that aims to change 
the amount or type of precipitation that falls from clouds by 
dispersing substances into the air that serve as cloud condensation or 
ice nuclei, which alter the microphysical processes within the cloud.  
 
 
 
The usual intent is to increase precipitation (rain or snow) 
 
 
 
PLEASE NOTE: 
As the clouds are formed at some height over the surface of the earth, 
they take various shapes. 
 
TYPES OF CLOUDS  
Clouds are of different types and they can be classified on the  basis of their 
?  Form  
? Altitude. 
ON THE BASIS OF FORM CLOUDS ARE KNOWN AS 
1) STRATIFORM CLOUDS  
 layered clouds  
2) CUMULIFORM CLOUDS   
massive clouds  
ON THE BASIS OF ALTITUDE CLOUDS ARE CALLED  
1. CIRRUS (HIGHEST CLOUDS)  
 2. ALTO (MEDIUM HEIGHT)  
3 . STRATO (LOW-LEVEL CLOUDS)  
 
 
 
CHARACTERISTICS  
HIGH CLOUDS  
They  occur at altitudes of 6000 to 12000 metres . 
CIRRUS CLOUDS  
 
Cirrus clouds are formed at high altitudes (8,000 - 12,000m).   
They are thin and detatched clouds having a feather.  
CIRROCUMULUS CLOUDS  
 
Thin, white patch, sheet or layer of cloud without shading, composed of 
very small elements in the form of grains, ripples, etc., merged or 
separate, and more or less regularly arranged; most of the elements 
have an apparent width of less than 1°. 
This shows ripples and presents the mackerel sky conditions  
CIRROSTRATUS CLOUDS  
Page 5


 
 
WATER IN THE ATMOSPHERE - 3 
CLOUDS  
Cloud is a mass of minute water droplets or tiny crystals of ice 
formed by the condensation of the water vapour in free air at 
considerable elevations. 
It simply means condensation takes place for clouds to form and 
water vapour is converted into water or ice particles.  
Clouds are visible accumulations of tiny water droplets or ice 
crystals in the Earth’s atmosphere. Clouds differ greatly in size, 
shape, and color. They can appear thin and wispy, or bulky and 
lumpy. 
 
Clouds usually appear white because the tiny water droplets 
inside them are tightly packed, reflecting most of the sunlight 
that hits them. White is how our eyes perceive all wavelengths of 
sunlight mixed together.  
 
When it’s about to rain, clouds darken because the water vapor 
is clumping together into raindrops, leaving larger spaces 
between drops of water. Less light is reflected. The rain cloud 
appears black or gray. 
 
NOTE: 
HYGROSCOPIC NUCLEI 
 
In order for cloud droplets to form it also necessary that microscopic 
particles of dust or smoke with a high affinity for water (hygroscopic 
particles) are present in as and serve as condensation nuclei .In the 
 
 
absence of hygroscope particles in the atmosphere condensation 
becomes difficult . 
 
SUPER COOLED MOISTURE 
Water vapour in the air fails to condense sometimes due to lack of 
hygroscopic particles or any other cause in spite of the as parcel having 
been cooled below the dew point is caged super-cooled moisture. This 
phenomenon is rare and generally confined to the upper parts of the 
troposphere.  
 
 
CLOUD CONDENSATION NUCLEI 
Cloud condensation nuclei or CCNs (also known as cloud seeds) are 
small particles typically 0.2 µm, or 1/100th the size of a cloud droplet  on 
which water vapor condenses. Water requires a non-gaseous surface to 
make the transition from a vapour to a liquid; this process is called 
condensation. In the atmosphere, this surface presents itself as tiny solid 
or liquid particles called CCNs. When no CCNs are present, water 
vapour can be supercooled at about -13°C (8°F) for 5–6 hours before 
droplets spontaneously form . 
 
CLOUD SEEDING 
The concept of cloud condensation nuclei is used in cloud seeding, that 
tries to encourage rainfall by seeding the air with condensation 
nuclei. 
Cloud seeding is a type of weather modification that aims to change 
the amount or type of precipitation that falls from clouds by 
dispersing substances into the air that serve as cloud condensation or 
ice nuclei, which alter the microphysical processes within the cloud.  
 
 
 
The usual intent is to increase precipitation (rain or snow) 
 
 
 
PLEASE NOTE: 
As the clouds are formed at some height over the surface of the earth, 
they take various shapes. 
 
TYPES OF CLOUDS  
Clouds are of different types and they can be classified on the  basis of their 
?  Form  
? Altitude. 
ON THE BASIS OF FORM CLOUDS ARE KNOWN AS 
1) STRATIFORM CLOUDS  
 layered clouds  
2) CUMULIFORM CLOUDS   
massive clouds  
ON THE BASIS OF ALTITUDE CLOUDS ARE CALLED  
1. CIRRUS (HIGHEST CLOUDS)  
 2. ALTO (MEDIUM HEIGHT)  
3 . STRATO (LOW-LEVEL CLOUDS)  
 
 
 
CHARACTERISTICS  
HIGH CLOUDS  
They  occur at altitudes of 6000 to 12000 metres . 
CIRRUS CLOUDS  
 
Cirrus clouds are formed at high altitudes (8,000 - 12,000m).   
They are thin and detatched clouds having a feather.  
CIRROCUMULUS CLOUDS  
 
Thin, white patch, sheet or layer of cloud without shading, composed of 
very small elements in the form of grains, ripples, etc., merged or 
separate, and more or less regularly arranged; most of the elements 
have an apparent width of less than 1°. 
This shows ripples and presents the mackerel sky conditions  
CIRROSTRATUS CLOUDS  
 
 
 
Transparent, whitish cloud veil of fibrous (hair-like) or smooth 
appearance, totally or partly covering the sky, and generally producing 
halo phenomena. 
MEDIUM CLOUDS  
They form at an attitude of 2100 to 6000 metres above the surface and are 
deeded into the categories of altostratus and the altocumulus clouds.  
ALTOSTRATUS CLOUDS  
 
The altostratus cloud produces a blanket layer covering vast areas of the 
sky.   
ALTOCUMULUS CLOUDS