Temperature - Notes | Geography for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
 
TEMPERATURE?  
The interaction of insolation with the atmosphere and the earth’s surface 
creates heat which is measured in terms of temperature.  
FACTORS CONTROLLING THE DISTRIBUTION OF 
TEMPERATURE  
LATITUDES OF THE PLACE  
 
The temperature of a place depends on the insolation receive in a place. 
Since the amount of insolation received by the ground surface decreases 
poleward from the equator i.e., from low latitudes towards high latitudes 
because the sun's rays become more and more oblique (slanting) poleward 
and hence air temperature also decreases poleward.  
EXCEPTION: 
The maximum temperature is not recorded on equator but rather 
than on 20 degree north.  
 
WHY? 
 
? Sizable amount of heat lost in evaporation at equator. 
? Vapor condenses in the latter part of the day to form cumulonimbus 
clouds (rain bearing clouds) leading to heavy rainfall.  
? Cloud cover reflects some part of insolation at equator. 
 
Page 2


 
 
TEMPERATURE?  
The interaction of insolation with the atmosphere and the earth’s surface 
creates heat which is measured in terms of temperature.  
FACTORS CONTROLLING THE DISTRIBUTION OF 
TEMPERATURE  
LATITUDES OF THE PLACE  
 
The temperature of a place depends on the insolation receive in a place. 
Since the amount of insolation received by the ground surface decreases 
poleward from the equator i.e., from low latitudes towards high latitudes 
because the sun's rays become more and more oblique (slanting) poleward 
and hence air temperature also decreases poleward.  
EXCEPTION: 
The maximum temperature is not recorded on equator but rather 
than on 20 degree north.  
 
WHY? 
 
? Sizable amount of heat lost in evaporation at equator. 
? Vapor condenses in the latter part of the day to form cumulonimbus 
clouds (rain bearing clouds) leading to heavy rainfall.  
? Cloud cover reflects some part of insolation at equator. 
 
 
 
NOTE: 
 Why not 20 degree south? 
? Because of continentality in Northern Hemisphere. 
 ALTITUDE OF THE PLACE  
 
 
? Temperature decreases height increases at 6.5 In Celsius per kilometer . 
WHY? 
? The lowest layer of the air contains more water vapour and dust 
particles and hence it absorbs larger amount of heat radiated from 
Earth's surface then upper layers . 
? As vs send higher in the atmosphere the amount of  heat gets lost to 
subsequent layer lying below . 
 
NATURE OF GROUND SURFACE/ GROUND SLOPES   
? The snow covered surface reflect most of incoming shortwave radiation( 
albedo). 
? Thick vegetative cover cuts off Insolation from reaching the ground 
surface.  
? The ground slope facing the sun receive more insolation because the 
sun's rays reach the surface more or less straight than leeward slope with 
sun rays reach more obliquely.  
Page 3


 
 
TEMPERATURE?  
The interaction of insolation with the atmosphere and the earth’s surface 
creates heat which is measured in terms of temperature.  
FACTORS CONTROLLING THE DISTRIBUTION OF 
TEMPERATURE  
LATITUDES OF THE PLACE  
 
The temperature of a place depends on the insolation receive in a place. 
Since the amount of insolation received by the ground surface decreases 
poleward from the equator i.e., from low latitudes towards high latitudes 
because the sun's rays become more and more oblique (slanting) poleward 
and hence air temperature also decreases poleward.  
EXCEPTION: 
The maximum temperature is not recorded on equator but rather 
than on 20 degree north.  
 
WHY? 
 
? Sizable amount of heat lost in evaporation at equator. 
? Vapor condenses in the latter part of the day to form cumulonimbus 
clouds (rain bearing clouds) leading to heavy rainfall.  
? Cloud cover reflects some part of insolation at equator. 
 
 
 
NOTE: 
 Why not 20 degree south? 
? Because of continentality in Northern Hemisphere. 
 ALTITUDE OF THE PLACE  
 
 
? Temperature decreases height increases at 6.5 In Celsius per kilometer . 
WHY? 
? The lowest layer of the air contains more water vapour and dust 
particles and hence it absorbs larger amount of heat radiated from 
Earth's surface then upper layers . 
? As vs send higher in the atmosphere the amount of  heat gets lost to 
subsequent layer lying below . 
 
NATURE OF GROUND SURFACE/ GROUND SLOPES   
? The snow covered surface reflect most of incoming shortwave radiation( 
albedo). 
? Thick vegetative cover cuts off Insolation from reaching the ground 
surface.  
? The ground slope facing the sun receive more insolation because the 
sun's rays reach the surface more or less straight than leeward slope with 
sun rays reach more obliquely.  
 
 
EXAMPLE: 
? In the Northern hemisphere, the south facing slopes of east west 
stretching mountain receive greater amount of insolation then the 
north facing slopes because of their exposure to the direct rays sun 
for longer duration.  (ADRET /UBAC SLOPE) 
 
 
DISTANCE FROM THE SEA  
? The Marine environment moderate the weather conditions of coastal 
areas . 
 CONCEPT:    
 LAND AND SEA BREEZE  
        Sea breeze in a day 
 
Sea breeze blows during the day and the land heats up faster than the sea. 
The air on land becomes less dense (i.e.warmer) and rises so the cooler air 
Page 4


 
 
TEMPERATURE?  
The interaction of insolation with the atmosphere and the earth’s surface 
creates heat which is measured in terms of temperature.  
FACTORS CONTROLLING THE DISTRIBUTION OF 
TEMPERATURE  
LATITUDES OF THE PLACE  
 
The temperature of a place depends on the insolation receive in a place. 
Since the amount of insolation received by the ground surface decreases 
poleward from the equator i.e., from low latitudes towards high latitudes 
because the sun's rays become more and more oblique (slanting) poleward 
and hence air temperature also decreases poleward.  
EXCEPTION: 
The maximum temperature is not recorded on equator but rather 
than on 20 degree north.  
 
WHY? 
 
? Sizable amount of heat lost in evaporation at equator. 
? Vapor condenses in the latter part of the day to form cumulonimbus 
clouds (rain bearing clouds) leading to heavy rainfall.  
? Cloud cover reflects some part of insolation at equator. 
 
 
 
NOTE: 
 Why not 20 degree south? 
? Because of continentality in Northern Hemisphere. 
 ALTITUDE OF THE PLACE  
 
 
? Temperature decreases height increases at 6.5 In Celsius per kilometer . 
WHY? 
? The lowest layer of the air contains more water vapour and dust 
particles and hence it absorbs larger amount of heat radiated from 
Earth's surface then upper layers . 
? As vs send higher in the atmosphere the amount of  heat gets lost to 
subsequent layer lying below . 
 
NATURE OF GROUND SURFACE/ GROUND SLOPES   
? The snow covered surface reflect most of incoming shortwave radiation( 
albedo). 
? Thick vegetative cover cuts off Insolation from reaching the ground 
surface.  
? The ground slope facing the sun receive more insolation because the 
sun's rays reach the surface more or less straight than leeward slope with 
sun rays reach more obliquely.  
 
 
EXAMPLE: 
? In the Northern hemisphere, the south facing slopes of east west 
stretching mountain receive greater amount of insolation then the 
north facing slopes because of their exposure to the direct rays sun 
for longer duration.  (ADRET /UBAC SLOPE) 
 
 
DISTANCE FROM THE SEA  
? The Marine environment moderate the weather conditions of coastal 
areas . 
 CONCEPT:    
 LAND AND SEA BREEZE  
        Sea breeze in a day 
 
Sea breeze blows during the day and the land heats up faster than the sea. 
The air on land becomes less dense (i.e.warmer) and rises so the cooler air 
 
 
over the sea which is denser(cooler) flows in to take the place of the warm 
air, causing a sea breeze. 
 
 Land breeze at night  
 
Land breeze blows during the night from land to sea and the land 
becomes cooler faster than the sea. The air above the sea becomes less 
dense (i.e. warmer) and rises. The cooler air from the land moves in to 
take its place. 
 DIURAL RANGE OF TEMPERATURE  
? Difference between the daily maximum and minimum temperature.  
? Compare marine climate with continental climate 
 
 PREVAILING WINDS  
a) land and sea breezes  
b) mountain and valley breeze.  
c) air masses  
CONCEPTS: 
AIR MASS?  
In meteorology, an air mass is a volume of air defined by its temperature 
and water vapor content. Air masses cover many hundreds or thousands of 
miles, and adapt to the characteristics of the surface below them. 
Page 5


 
 
TEMPERATURE?  
The interaction of insolation with the atmosphere and the earth’s surface 
creates heat which is measured in terms of temperature.  
FACTORS CONTROLLING THE DISTRIBUTION OF 
TEMPERATURE  
LATITUDES OF THE PLACE  
 
The temperature of a place depends on the insolation receive in a place. 
Since the amount of insolation received by the ground surface decreases 
poleward from the equator i.e., from low latitudes towards high latitudes 
because the sun's rays become more and more oblique (slanting) poleward 
and hence air temperature also decreases poleward.  
EXCEPTION: 
The maximum temperature is not recorded on equator but rather 
than on 20 degree north.  
 
WHY? 
 
? Sizable amount of heat lost in evaporation at equator. 
? Vapor condenses in the latter part of the day to form cumulonimbus 
clouds (rain bearing clouds) leading to heavy rainfall.  
? Cloud cover reflects some part of insolation at equator. 
 
 
 
NOTE: 
 Why not 20 degree south? 
? Because of continentality in Northern Hemisphere. 
 ALTITUDE OF THE PLACE  
 
 
? Temperature decreases height increases at 6.5 In Celsius per kilometer . 
WHY? 
? The lowest layer of the air contains more water vapour and dust 
particles and hence it absorbs larger amount of heat radiated from 
Earth's surface then upper layers . 
? As vs send higher in the atmosphere the amount of  heat gets lost to 
subsequent layer lying below . 
 
NATURE OF GROUND SURFACE/ GROUND SLOPES   
? The snow covered surface reflect most of incoming shortwave radiation( 
albedo). 
? Thick vegetative cover cuts off Insolation from reaching the ground 
surface.  
? The ground slope facing the sun receive more insolation because the 
sun's rays reach the surface more or less straight than leeward slope with 
sun rays reach more obliquely.  
 
 
EXAMPLE: 
? In the Northern hemisphere, the south facing slopes of east west 
stretching mountain receive greater amount of insolation then the 
north facing slopes because of their exposure to the direct rays sun 
for longer duration.  (ADRET /UBAC SLOPE) 
 
 
DISTANCE FROM THE SEA  
? The Marine environment moderate the weather conditions of coastal 
areas . 
 CONCEPT:    
 LAND AND SEA BREEZE  
        Sea breeze in a day 
 
Sea breeze blows during the day and the land heats up faster than the sea. 
The air on land becomes less dense (i.e.warmer) and rises so the cooler air 
 
 
over the sea which is denser(cooler) flows in to take the place of the warm 
air, causing a sea breeze. 
 
 Land breeze at night  
 
Land breeze blows during the night from land to sea and the land 
becomes cooler faster than the sea. The air above the sea becomes less 
dense (i.e. warmer) and rises. The cooler air from the land moves in to 
take its place. 
 DIURAL RANGE OF TEMPERATURE  
? Difference between the daily maximum and minimum temperature.  
? Compare marine climate with continental climate 
 
 PREVAILING WINDS  
a) land and sea breezes  
b) mountain and valley breeze.  
c) air masses  
CONCEPTS: 
AIR MASS?  
In meteorology, an air mass is a volume of air defined by its temperature 
and water vapor content. Air masses cover many hundreds or thousands of 
miles, and adapt to the characteristics of the surface below them. 
 
 
VALLEY BREEZE AND MOUNTAIN BREEZE 
 
During the day, the air over the mountain slope heats up more than the air 
at the foot of the mountain. The warm air over the slope reduces in 
density. A low pressure is created at the top of the mountain and high 
pressure from the cool air below forces a cool breeze to move upward. 
This condition generates a breeze which we call Valley breeze, and it is 
very common during warmer months when there is a lot of heating from 
the sun. 
In the night, it is a lot cooler. So the air at the upper slope of the mountain 
cools off very quickly and becomes dense. A high pressure is created. At 
this time, the air at the valley floor is a lot warmer (low pressure) and is 
forced to give way to colder air moving down the slope towards the valley 
floor. This is called mountain breeze, and it is a lot common in the colder 
months when there is less warming from the sun. 
NATURE OF LAND AND WATER  
? Land becomes warm and cold quickly than water body  
WHY SO? 
? Rays penetrate to a depth of only 3 feet in land but they can penetrate 
to several meters in water with the heat getting spread to larger areas.  
? land is static but water is mobile. Hence there is slow redistribution of 
heat in the land.   
? Specific heat capacity of water is much greater than land.