Climate vs Weather | Geography for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
 
CLIMATE VS WEATHER 
Weather refers to short-term changes in the atmosphere. 
Climate describes what the weather is like over a long period of time in a 
specific area. 
  
WHAT IS ATMOSPHERE? 
 
 
Atmosphere is a thick gaseous envelope that surrounds the Earth. 
Atmosphere is a mixture of different gases and it envelopes the earth all round.  
The air is an integral part of the earth’s mass and 99 per cent of the total mass 
of the atmosphere is confined to the height of 32 km from the earth’s 
surface.  
 
COMPOSITION OF THE ATMOSPHERE 
The atmosphere is composed of gases, water vapour and dust particles. 
The proportion of gases changes in the higher layers of the atmosphere in such 
a way that oxygen will be almost in negligible quantity at the height of 120 
km.  Similarly, carbon dioxide and water vapour are found only up to 90 
km from the surface of the earth. 
Page 2


 
 
CLIMATE VS WEATHER 
Weather refers to short-term changes in the atmosphere. 
Climate describes what the weather is like over a long period of time in a 
specific area. 
  
WHAT IS ATMOSPHERE? 
 
 
Atmosphere is a thick gaseous envelope that surrounds the Earth. 
Atmosphere is a mixture of different gases and it envelopes the earth all round.  
The air is an integral part of the earth’s mass and 99 per cent of the total mass 
of the atmosphere is confined to the height of 32 km from the earth’s 
surface.  
 
COMPOSITION OF THE ATMOSPHERE 
The atmosphere is composed of gases, water vapour and dust particles. 
The proportion of gases changes in the higher layers of the atmosphere in such 
a way that oxygen will be almost in negligible quantity at the height of 120 
km.  Similarly, carbon dioxide and water vapour are found only up to 90 
km from the surface of the earth. 
 
 
 
 
GASES  
Carbon dioxide is meteorologically a very important gas as it is transparent 
to the incoming solar radiation but opaque to the outgoing terrestrial 
radiation. It absorbs a part of terrestrial radiation and reflects back some 
part of it towards the earth’s surface. It is largely responsible for the green 
house effect. 
Ozone is another important component of the atmosphere found between 10 
and 50 km above the earth’s surface and acts as a filter and absorbs the 
ultra-violet rays radiating from the sun and prevents them from reaching 
the surface of the earth. 
Water vapour is also a variable gas in the atmosphere, which decreases with 
altitude. In the warm and wet tropics, it may account for four per cent of 
the air by volume, while in the dry and cold areas of desert and polar 
regions, it may be less than one per cent of the air. Water vapour also 
decreases from the equator towards the poles. It also absorbs parts of the 
insolation from the sun and preserves the earth’s radiated heat. It thus, 
acts like a blanket allowing the earth neither to become too cold nor too 
hot.  
Dust Particles : Atmosphere has a sufficient capacity to keep small solid 
particles, which may originate from different sources and include sea 
salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of 
Page 3


 
 
CLIMATE VS WEATHER 
Weather refers to short-term changes in the atmosphere. 
Climate describes what the weather is like over a long period of time in a 
specific area. 
  
WHAT IS ATMOSPHERE? 
 
 
Atmosphere is a thick gaseous envelope that surrounds the Earth. 
Atmosphere is a mixture of different gases and it envelopes the earth all round.  
The air is an integral part of the earth’s mass and 99 per cent of the total mass 
of the atmosphere is confined to the height of 32 km from the earth’s 
surface.  
 
COMPOSITION OF THE ATMOSPHERE 
The atmosphere is composed of gases, water vapour and dust particles. 
The proportion of gases changes in the higher layers of the atmosphere in such 
a way that oxygen will be almost in negligible quantity at the height of 120 
km.  Similarly, carbon dioxide and water vapour are found only up to 90 
km from the surface of the earth. 
 
 
 
 
GASES  
Carbon dioxide is meteorologically a very important gas as it is transparent 
to the incoming solar radiation but opaque to the outgoing terrestrial 
radiation. It absorbs a part of terrestrial radiation and reflects back some 
part of it towards the earth’s surface. It is largely responsible for the green 
house effect. 
Ozone is another important component of the atmosphere found between 10 
and 50 km above the earth’s surface and acts as a filter and absorbs the 
ultra-violet rays radiating from the sun and prevents them from reaching 
the surface of the earth. 
Water vapour is also a variable gas in the atmosphere, which decreases with 
altitude. In the warm and wet tropics, it may account for four per cent of 
the air by volume, while in the dry and cold areas of desert and polar 
regions, it may be less than one per cent of the air. Water vapour also 
decreases from the equator towards the poles. It also absorbs parts of the 
insolation from the sun and preserves the earth’s radiated heat. It thus, 
acts like a blanket allowing the earth neither to become too cold nor too 
hot.  
Dust Particles : Atmosphere has a sufficient capacity to keep small solid 
particles, which may originate from different sources and include sea 
salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of 
 
 
meteors. Dust particles are generally concentrated in the lower layers of the 
atmosphere; yet, convectional air currents may transport them to great heights. 
The higher concentration of dust particles is found in subtropical and 
temperate regions due to dry winds in comparison to equatorial and polar 
regions. Dust and salt particles act as hygroscopic nuclei around which 
water vapour condenses to produce clouds. 
 
 
 
 
 
STRUCTURE OF THE ATMOSPHERE 
  
 
Page 4


 
 
CLIMATE VS WEATHER 
Weather refers to short-term changes in the atmosphere. 
Climate describes what the weather is like over a long period of time in a 
specific area. 
  
WHAT IS ATMOSPHERE? 
 
 
Atmosphere is a thick gaseous envelope that surrounds the Earth. 
Atmosphere is a mixture of different gases and it envelopes the earth all round.  
The air is an integral part of the earth’s mass and 99 per cent of the total mass 
of the atmosphere is confined to the height of 32 km from the earth’s 
surface.  
 
COMPOSITION OF THE ATMOSPHERE 
The atmosphere is composed of gases, water vapour and dust particles. 
The proportion of gases changes in the higher layers of the atmosphere in such 
a way that oxygen will be almost in negligible quantity at the height of 120 
km.  Similarly, carbon dioxide and water vapour are found only up to 90 
km from the surface of the earth. 
 
 
 
 
GASES  
Carbon dioxide is meteorologically a very important gas as it is transparent 
to the incoming solar radiation but opaque to the outgoing terrestrial 
radiation. It absorbs a part of terrestrial radiation and reflects back some 
part of it towards the earth’s surface. It is largely responsible for the green 
house effect. 
Ozone is another important component of the atmosphere found between 10 
and 50 km above the earth’s surface and acts as a filter and absorbs the 
ultra-violet rays radiating from the sun and prevents them from reaching 
the surface of the earth. 
Water vapour is also a variable gas in the atmosphere, which decreases with 
altitude. In the warm and wet tropics, it may account for four per cent of 
the air by volume, while in the dry and cold areas of desert and polar 
regions, it may be less than one per cent of the air. Water vapour also 
decreases from the equator towards the poles. It also absorbs parts of the 
insolation from the sun and preserves the earth’s radiated heat. It thus, 
acts like a blanket allowing the earth neither to become too cold nor too 
hot.  
Dust Particles : Atmosphere has a sufficient capacity to keep small solid 
particles, which may originate from different sources and include sea 
salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of 
 
 
meteors. Dust particles are generally concentrated in the lower layers of the 
atmosphere; yet, convectional air currents may transport them to great heights. 
The higher concentration of dust particles is found in subtropical and 
temperate regions due to dry winds in comparison to equatorial and polar 
regions. Dust and salt particles act as hygroscopic nuclei around which 
water vapour condenses to produce clouds. 
 
 
 
 
 
STRUCTURE OF THE ATMOSPHERE 
  
 
 
 
 The atmosphere consists of different layers with varying density and 
temperature.  Density is highest near the surface of the earth and 
decreases with increasing altitude.   
The column of atmosphere is divided into five different layers depending 
upon the temperature condition : 
1. Troposphere  
2. Stratosphere  
3. Mesosphere  
4. Thermosphere  
5. Exosphere  
 
TROPOSPHERE  
The troposphere is the lowermost layer of the atmosphere. 
 Its average height is 13 km and extends roughly to a height of 8 km near 
the poles and about 18 km at the equator. 
 Thickness of the troposphere is greatest at the equator because heat is 
transported to great heights by strong convectional currents. This layer 
contains dust particles and water vapour. 
 
    WHY IS THE HEIGHT OF TROPOPAUSE 
MAXIMUM AROUND THE EQUATOR AND MINIMUM AROUND 
THE POLES?  
1) Strong convection current is produced  at equator because of 
excessive heating and this will put the tropopause upward.  
2) The air gets very cold becomes dense and start sinking at poles. 
3) Gravity increases from equator to poles as the earth is not a perfect 
sphere. That means the gravitational force is more over poles.  Hence 
Page 5


 
 
CLIMATE VS WEATHER 
Weather refers to short-term changes in the atmosphere. 
Climate describes what the weather is like over a long period of time in a 
specific area. 
  
WHAT IS ATMOSPHERE? 
 
 
Atmosphere is a thick gaseous envelope that surrounds the Earth. 
Atmosphere is a mixture of different gases and it envelopes the earth all round.  
The air is an integral part of the earth’s mass and 99 per cent of the total mass 
of the atmosphere is confined to the height of 32 km from the earth’s 
surface.  
 
COMPOSITION OF THE ATMOSPHERE 
The atmosphere is composed of gases, water vapour and dust particles. 
The proportion of gases changes in the higher layers of the atmosphere in such 
a way that oxygen will be almost in negligible quantity at the height of 120 
km.  Similarly, carbon dioxide and water vapour are found only up to 90 
km from the surface of the earth. 
 
 
 
 
GASES  
Carbon dioxide is meteorologically a very important gas as it is transparent 
to the incoming solar radiation but opaque to the outgoing terrestrial 
radiation. It absorbs a part of terrestrial radiation and reflects back some 
part of it towards the earth’s surface. It is largely responsible for the green 
house effect. 
Ozone is another important component of the atmosphere found between 10 
and 50 km above the earth’s surface and acts as a filter and absorbs the 
ultra-violet rays radiating from the sun and prevents them from reaching 
the surface of the earth. 
Water vapour is also a variable gas in the atmosphere, which decreases with 
altitude. In the warm and wet tropics, it may account for four per cent of 
the air by volume, while in the dry and cold areas of desert and polar 
regions, it may be less than one per cent of the air. Water vapour also 
decreases from the equator towards the poles. It also absorbs parts of the 
insolation from the sun and preserves the earth’s radiated heat. It thus, 
acts like a blanket allowing the earth neither to become too cold nor too 
hot.  
Dust Particles : Atmosphere has a sufficient capacity to keep small solid 
particles, which may originate from different sources and include sea 
salts, fine soil, smoke-soot, ash, pollen, dust and disintegrated particles of 
 
 
meteors. Dust particles are generally concentrated in the lower layers of the 
atmosphere; yet, convectional air currents may transport them to great heights. 
The higher concentration of dust particles is found in subtropical and 
temperate regions due to dry winds in comparison to equatorial and polar 
regions. Dust and salt particles act as hygroscopic nuclei around which 
water vapour condenses to produce clouds. 
 
 
 
 
 
STRUCTURE OF THE ATMOSPHERE 
  
 
 
 
 The atmosphere consists of different layers with varying density and 
temperature.  Density is highest near the surface of the earth and 
decreases with increasing altitude.   
The column of atmosphere is divided into five different layers depending 
upon the temperature condition : 
1. Troposphere  
2. Stratosphere  
3. Mesosphere  
4. Thermosphere  
5. Exosphere  
 
TROPOSPHERE  
The troposphere is the lowermost layer of the atmosphere. 
 Its average height is 13 km and extends roughly to a height of 8 km near 
the poles and about 18 km at the equator. 
 Thickness of the troposphere is greatest at the equator because heat is 
transported to great heights by strong convectional currents. This layer 
contains dust particles and water vapour. 
 
    WHY IS THE HEIGHT OF TROPOPAUSE 
MAXIMUM AROUND THE EQUATOR AND MINIMUM AROUND 
THE POLES?  
1) Strong convection current is produced  at equator because of 
excessive heating and this will put the tropopause upward.  
2) The air gets very cold becomes dense and start sinking at poles. 
3) Gravity increases from equator to poles as the earth is not a perfect 
sphere. That means the gravitational force is more over poles.  Hence 
 
 
the atmosphere is pulled with more force near poles than at the 
equator leading to the contraction of the atmosphere at the poles 
and expansion at the equator.  
4) the centrifugal force due to Earth's rotation is maximum at equator 
because the speed of the rotating Earth is greatest at the equator . 
Thus the atmosphere tends to bulged out  at equator because of the 
force.  
  
 All changes in climate and weather take place in this layer. It is also 
meteorologically the most significant zone in the entire atmosphere 
(Almost all the weather phenomena like rainfall, fog and hailstorm etc. 
are confined to this layer). 
This is the most important layer for all biological activity. 
 The temperature in this layer decreases at the rate of 1°C for every 165m 
of height. The fall in temperature is called ‘lapse rate’. 
   WHY TEMPERATURE INVERSION? 
1) Ascend higher in the atmosphere the amount of heat gets lost to 
the subsecutive layer lying below.  
2) Air pressure is higher in the lower portion of the atmosphere 
near the Earth's surface because of the weight of all the overlying 
layers above. Thus density of air decreases as we move upward 
(gravity) 
3) The lower layer of air contains more water vapour and dust 
particles then the layers above and hence it absorbs large 
amount of heat radiated from the Earth surface then the upper 
layers  
 
TROPOPAUSE: