Water in Atmosphere- 4 | Geography for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
 
WATER IN THE ATMOSPHERE - 4 
PRECIPITATION   
The process of continuous condensation in free air helps the condensed 
particles to grow in size.  
When the resistance of the air fails to hold them against the force of 
gravity, they fall on to the earth’s surface.  
So after the condensation of water vapour, the release of moisture is 
known as precipitation.  
This may take place in liquid or solid form. 
The term precipitation refers to falling of water, snow or hail from the 
clouds and it results when condensation is occurring rapidly within a 
cloud.  
FORMS OF PRECIPITATION  
Precipitation may occur in different forms.  
Rainfall, Sleet, Snowfall and hail are the common forms of precipitation.  
RAINFALL 
The precipitation in the form of water is called rainfall.  
Rainfall occurs when the dew point of air is above the freezing point so 
that the condensing moisture is converted to water droplets. 
SNOWFALL 
 When the temperature is lower than the 0 degree C, precipitation takes 
place in the form of fine flakes of snow and is called snowfall.  
The dew point of air for this to occur should be below the freezing point . 
Page 2


 
 
WATER IN THE ATMOSPHERE - 4 
PRECIPITATION   
The process of continuous condensation in free air helps the condensed 
particles to grow in size.  
When the resistance of the air fails to hold them against the force of 
gravity, they fall on to the earth’s surface.  
So after the condensation of water vapour, the release of moisture is 
known as precipitation.  
This may take place in liquid or solid form. 
The term precipitation refers to falling of water, snow or hail from the 
clouds and it results when condensation is occurring rapidly within a 
cloud.  
FORMS OF PRECIPITATION  
Precipitation may occur in different forms.  
Rainfall, Sleet, Snowfall and hail are the common forms of precipitation.  
RAINFALL 
The precipitation in the form of water is called rainfall.  
Rainfall occurs when the dew point of air is above the freezing point so 
that the condensing moisture is converted to water droplets. 
SNOWFALL 
 When the temperature is lower than the 0 degree C, precipitation takes 
place in the form of fine flakes of snow and is called snowfall.  
The dew point of air for this to occur should be below the freezing point . 
 
 
TYPES OF PRECIPITATION  
On the basis of origin, rainfall may be classified into three main types – the 
convectional, orographic or relief and the cyclonic or frontal 
1. Convectional.  
2. Orographic, 
3. Cyclonic or Frontal.  
CONVECTIONAL PRECIPITATION  
 
As the name suggests convectional precipitation is a result of convection.  
The, air on being heated, becomes light and rises up in convection 
currents.   
If the cooling due to uplift of air is sufficient, it may lead to condensation 
and precipitation. This type of precipitation is called convectional 
precipitation.   
It is very common in the equatorial regions and interior parts of the continents, 
particularly in the northern hemisphere. 
OROGRAPHIC PRECIPITATION  
Page 3


 
 
WATER IN THE ATMOSPHERE - 4 
PRECIPITATION   
The process of continuous condensation in free air helps the condensed 
particles to grow in size.  
When the resistance of the air fails to hold them against the force of 
gravity, they fall on to the earth’s surface.  
So after the condensation of water vapour, the release of moisture is 
known as precipitation.  
This may take place in liquid or solid form. 
The term precipitation refers to falling of water, snow or hail from the 
clouds and it results when condensation is occurring rapidly within a 
cloud.  
FORMS OF PRECIPITATION  
Precipitation may occur in different forms.  
Rainfall, Sleet, Snowfall and hail are the common forms of precipitation.  
RAINFALL 
The precipitation in the form of water is called rainfall.  
Rainfall occurs when the dew point of air is above the freezing point so 
that the condensing moisture is converted to water droplets. 
SNOWFALL 
 When the temperature is lower than the 0 degree C, precipitation takes 
place in the form of fine flakes of snow and is called snowfall.  
The dew point of air for this to occur should be below the freezing point . 
 
 
TYPES OF PRECIPITATION  
On the basis of origin, rainfall may be classified into three main types – the 
convectional, orographic or relief and the cyclonic or frontal 
1. Convectional.  
2. Orographic, 
3. Cyclonic or Frontal.  
CONVECTIONAL PRECIPITATION  
 
As the name suggests convectional precipitation is a result of convection.  
The, air on being heated, becomes light and rises up in convection 
currents.   
If the cooling due to uplift of air is sufficient, it may lead to condensation 
and precipitation. This type of precipitation is called convectional 
precipitation.   
It is very common in the equatorial regions and interior parts of the continents, 
particularly in the northern hemisphere. 
OROGRAPHIC PRECIPITATION  
 
 
 
Orographic precipitation is caused by landforms. It is sometimes also called 
mountain precipitation 
When the saturated air mass comes across a mountain, it is forced to 
ascend and as it rises, it expands; the temperature falls, and the moisture 
is condensed.  
After giving rain on the windward side, when these winds reach the other 
slope, they descend, and their temperature rises.  
Then their capacity to take in moisture increases and hence, these leeward 
slopes remain rainless and dry.  
The chief characteristic of this sort of rain is that the windward slopes 
receive greater rainfall. 
The area situated on the leeward side, which gets less rainfall is known as 
the rain-shadow area.   
It is also known as the relief rain. 
Much of the precipitation in the northern plains of India during the southwest 
monsoon season and most of the precipitation in the northeast India is of this 
type.  
CYCLONIC RAINFALL 
ALREADY COVERED – YOU CAN REFER TO THE 
CORRESPONDING LECTURES 
Page 4


 
 
WATER IN THE ATMOSPHERE - 4 
PRECIPITATION   
The process of continuous condensation in free air helps the condensed 
particles to grow in size.  
When the resistance of the air fails to hold them against the force of 
gravity, they fall on to the earth’s surface.  
So after the condensation of water vapour, the release of moisture is 
known as precipitation.  
This may take place in liquid or solid form. 
The term precipitation refers to falling of water, snow or hail from the 
clouds and it results when condensation is occurring rapidly within a 
cloud.  
FORMS OF PRECIPITATION  
Precipitation may occur in different forms.  
Rainfall, Sleet, Snowfall and hail are the common forms of precipitation.  
RAINFALL 
The precipitation in the form of water is called rainfall.  
Rainfall occurs when the dew point of air is above the freezing point so 
that the condensing moisture is converted to water droplets. 
SNOWFALL 
 When the temperature is lower than the 0 degree C, precipitation takes 
place in the form of fine flakes of snow and is called snowfall.  
The dew point of air for this to occur should be below the freezing point . 
 
 
TYPES OF PRECIPITATION  
On the basis of origin, rainfall may be classified into three main types – the 
convectional, orographic or relief and the cyclonic or frontal 
1. Convectional.  
2. Orographic, 
3. Cyclonic or Frontal.  
CONVECTIONAL PRECIPITATION  
 
As the name suggests convectional precipitation is a result of convection.  
The, air on being heated, becomes light and rises up in convection 
currents.   
If the cooling due to uplift of air is sufficient, it may lead to condensation 
and precipitation. This type of precipitation is called convectional 
precipitation.   
It is very common in the equatorial regions and interior parts of the continents, 
particularly in the northern hemisphere. 
OROGRAPHIC PRECIPITATION  
 
 
 
Orographic precipitation is caused by landforms. It is sometimes also called 
mountain precipitation 
When the saturated air mass comes across a mountain, it is forced to 
ascend and as it rises, it expands; the temperature falls, and the moisture 
is condensed.  
After giving rain on the windward side, when these winds reach the other 
slope, they descend, and their temperature rises.  
Then their capacity to take in moisture increases and hence, these leeward 
slopes remain rainless and dry.  
The chief characteristic of this sort of rain is that the windward slopes 
receive greater rainfall. 
The area situated on the leeward side, which gets less rainfall is known as 
the rain-shadow area.   
It is also known as the relief rain. 
Much of the precipitation in the northern plains of India during the southwest 
monsoon season and most of the precipitation in the northeast India is of this 
type.  
CYCLONIC RAINFALL 
ALREADY COVERED – YOU CAN REFER TO THE 
CORRESPONDING LECTURES 
 
 
ADDITIONAL INFO: 
It is called virage(virga) when raindrops evaporate before reaching the 
earth while passing through dry air. 
 
 
 
DISTRIBUTION OF RAINFALL 
Different places on the earth’s surface receive different amounts of 
rainfall in a year and that too in different seasons.  
In general, as we proceed from the equator towards the poles, rainfall goes 
on decreasing steadily.  
The coastal areas of the world receive greater amounts of rainfall than the 
interior of the continents. The rainfall is more over the oceans than on the 
landmasses of the world because of being great sources of water. 
(COASTAL RAINFALL) 
 
 
 
 
Page 5


 
 
WATER IN THE ATMOSPHERE - 4 
PRECIPITATION   
The process of continuous condensation in free air helps the condensed 
particles to grow in size.  
When the resistance of the air fails to hold them against the force of 
gravity, they fall on to the earth’s surface.  
So after the condensation of water vapour, the release of moisture is 
known as precipitation.  
This may take place in liquid or solid form. 
The term precipitation refers to falling of water, snow or hail from the 
clouds and it results when condensation is occurring rapidly within a 
cloud.  
FORMS OF PRECIPITATION  
Precipitation may occur in different forms.  
Rainfall, Sleet, Snowfall and hail are the common forms of precipitation.  
RAINFALL 
The precipitation in the form of water is called rainfall.  
Rainfall occurs when the dew point of air is above the freezing point so 
that the condensing moisture is converted to water droplets. 
SNOWFALL 
 When the temperature is lower than the 0 degree C, precipitation takes 
place in the form of fine flakes of snow and is called snowfall.  
The dew point of air for this to occur should be below the freezing point . 
 
 
TYPES OF PRECIPITATION  
On the basis of origin, rainfall may be classified into three main types – the 
convectional, orographic or relief and the cyclonic or frontal 
1. Convectional.  
2. Orographic, 
3. Cyclonic or Frontal.  
CONVECTIONAL PRECIPITATION  
 
As the name suggests convectional precipitation is a result of convection.  
The, air on being heated, becomes light and rises up in convection 
currents.   
If the cooling due to uplift of air is sufficient, it may lead to condensation 
and precipitation. This type of precipitation is called convectional 
precipitation.   
It is very common in the equatorial regions and interior parts of the continents, 
particularly in the northern hemisphere. 
OROGRAPHIC PRECIPITATION  
 
 
 
Orographic precipitation is caused by landforms. It is sometimes also called 
mountain precipitation 
When the saturated air mass comes across a mountain, it is forced to 
ascend and as it rises, it expands; the temperature falls, and the moisture 
is condensed.  
After giving rain on the windward side, when these winds reach the other 
slope, they descend, and their temperature rises.  
Then their capacity to take in moisture increases and hence, these leeward 
slopes remain rainless and dry.  
The chief characteristic of this sort of rain is that the windward slopes 
receive greater rainfall. 
The area situated on the leeward side, which gets less rainfall is known as 
the rain-shadow area.   
It is also known as the relief rain. 
Much of the precipitation in the northern plains of India during the southwest 
monsoon season and most of the precipitation in the northeast India is of this 
type.  
CYCLONIC RAINFALL 
ALREADY COVERED – YOU CAN REFER TO THE 
CORRESPONDING LECTURES 
 
 
ADDITIONAL INFO: 
It is called virage(virga) when raindrops evaporate before reaching the 
earth while passing through dry air. 
 
 
 
DISTRIBUTION OF RAINFALL 
Different places on the earth’s surface receive different amounts of 
rainfall in a year and that too in different seasons.  
In general, as we proceed from the equator towards the poles, rainfall goes 
on decreasing steadily.  
The coastal areas of the world receive greater amounts of rainfall than the 
interior of the continents. The rainfall is more over the oceans than on the 
landmasses of the world because of being great sources of water. 
(COASTAL RAINFALL) 
 
 
 
 
 
 
Between the latitudes 35 N and 40 N and S of the equator, the rain is 
heavier on the eastern coasts and goes on decreasing towards the west.  
(TRADE WINDS) 
But, between 45 N and 65 N and S of equator, due to the westerlies, the 
rainfall is first received on the western margins of the continents and it 
goes on decreasing towards the east. (WESTERLIES) 
Wherever mountains run parallel to the coast, the rain is greater on the 
coastal plain, on the windward side and it decreases towards the leeward 
side. (OROGRAPHIC RAINFALL) 
 
ATTEMPT A QUESTION ON YOUR END 
Write a note on Global Distribution of Rainfall.  
It will not be evaluated . 
This question is for you to evaluate your concepts in Climatology. 
 
HINT: 
IMAGINE ACCORDING TO THIS