Selina Textbook Solutions: Insolation | Geography Class 9 ICSE PDF Download

 Page 1


Insolation 
Exercises 
I. Short Answer Questions. 
Question 1. 
What is solar radiation ? What is its significance for the earth ? 
Answer: 
The sun continuously radiates heat and light energy in all the directions. It is known as 
solar radiation. Solar radiation is the only primary source of light and heat on the earth. 
The earth receives its heat from solar radiation which is a tiny fraction of the radiated 
energy of the sun. 
Question 2. 
What is meant by insolation ? State two of its main characteristics. 
Answer: 
The amount of solar energy received by the earth is called insolation, but only one part 
out of two billion parts reaches the earth. So, out of total 100% solar energy only 51% 
reaches the earth, 35% reflected back to into space and only 14% is absorbed by the 
ozone layer. 
Question 3. 
State two advantages of convectional heating of the atmosphere. 
Answer: 
Convectional heating of the atmosphere is done by heating up the layer of air touching 
land surface and rising up to warm up the upper layer, while the cold wind sinks down 
and again heated up by the terrestrial radiation. This circulation causes formation of 
clouds, rainfall and mild changes in climatic behaviour. 
Question 4. 
Name four factors that affect the temperature of a place. 
Answer: 
The four factors that affect the temperature of a place are : 
1. Latitude 
2. Distance from the sea. 
3. Altitude 
4. Wind direction 
5. Natural vegetation 
 
Page 2


Insolation 
Exercises 
I. Short Answer Questions. 
Question 1. 
What is solar radiation ? What is its significance for the earth ? 
Answer: 
The sun continuously radiates heat and light energy in all the directions. It is known as 
solar radiation. Solar radiation is the only primary source of light and heat on the earth. 
The earth receives its heat from solar radiation which is a tiny fraction of the radiated 
energy of the sun. 
Question 2. 
What is meant by insolation ? State two of its main characteristics. 
Answer: 
The amount of solar energy received by the earth is called insolation, but only one part 
out of two billion parts reaches the earth. So, out of total 100% solar energy only 51% 
reaches the earth, 35% reflected back to into space and only 14% is absorbed by the 
ozone layer. 
Question 3. 
State two advantages of convectional heating of the atmosphere. 
Answer: 
Convectional heating of the atmosphere is done by heating up the layer of air touching 
land surface and rising up to warm up the upper layer, while the cold wind sinks down 
and again heated up by the terrestrial radiation. This circulation causes formation of 
clouds, rainfall and mild changes in climatic behaviour. 
Question 4. 
Name four factors that affect the temperature of a place. 
Answer: 
The four factors that affect the temperature of a place are : 
1. Latitude 
2. Distance from the sea. 
3. Altitude 
4. Wind direction 
5. Natural vegetation 
 
Question 5. 
How does the distance from the sea affect the distribution of temperature ? 
Answer: 
Due to the physical property of water, which is heated up and cooled down slowly with 
respect to the land. So, the coastal areas experience mild climate with least range of 
temperature, while the regions far from the sea are affected by extreme climate with 
maximum range of temperature. 
Question 6. 
State the pattern of temperature in mid latitudes. 
Answer: 
Due to spherical shape of the earth, temperature zone gets less insolation resulting in 
moderate climate with normal temperature ranging from 15°C to 30°C. The duration of 
sunshine is greater in summer than winter. So the summer is warm and winter is cold. 
Question 7. 
How would the breezes that blow during the day and those that blow during the night 
affect the temperature of a place situated in the coastal region ? 
Answer: 
During the day the sea breeze blowing from sea towards land keeps the coastal region 
cool and during the night land breeze blowing from land towards sea makes the sea 
cooler. This interchange of breeze maintains the heat balance resulting in the mild 
climate of the coastal regions with lower daily and annual ranges of temperature. 
Question 8. 
What difference is there in the temperatures on a mountain and on a sea shore ? 
Answer: 
The rate of decrease of temperature is 1°C for every 166 metres, the temperatures on a 
mountain are for lesser than the temperatures on a sea shore which is nearly at zero 
height. 
Question 9. 
Why is India cooler in December than in July ? 
Answer: 
Tropic of Cancer passes midway across India, so, there is summer season in July, while 
in December the sun is vertical on the Tropic of Capricorn in southern hemisphere, so 
India experiences winter season. So naturally December is cooler than July. 
Question 10. 
State two chief characteristics of the Temperate zone. 
Answer: 
Medium temperature and medium rainfall due to slanting rays of the sun and less 
evaporation. 
Page 3


Insolation 
Exercises 
I. Short Answer Questions. 
Question 1. 
What is solar radiation ? What is its significance for the earth ? 
Answer: 
The sun continuously radiates heat and light energy in all the directions. It is known as 
solar radiation. Solar radiation is the only primary source of light and heat on the earth. 
The earth receives its heat from solar radiation which is a tiny fraction of the radiated 
energy of the sun. 
Question 2. 
What is meant by insolation ? State two of its main characteristics. 
Answer: 
The amount of solar energy received by the earth is called insolation, but only one part 
out of two billion parts reaches the earth. So, out of total 100% solar energy only 51% 
reaches the earth, 35% reflected back to into space and only 14% is absorbed by the 
ozone layer. 
Question 3. 
State two advantages of convectional heating of the atmosphere. 
Answer: 
Convectional heating of the atmosphere is done by heating up the layer of air touching 
land surface and rising up to warm up the upper layer, while the cold wind sinks down 
and again heated up by the terrestrial radiation. This circulation causes formation of 
clouds, rainfall and mild changes in climatic behaviour. 
Question 4. 
Name four factors that affect the temperature of a place. 
Answer: 
The four factors that affect the temperature of a place are : 
1. Latitude 
2. Distance from the sea. 
3. Altitude 
4. Wind direction 
5. Natural vegetation 
 
Question 5. 
How does the distance from the sea affect the distribution of temperature ? 
Answer: 
Due to the physical property of water, which is heated up and cooled down slowly with 
respect to the land. So, the coastal areas experience mild climate with least range of 
temperature, while the regions far from the sea are affected by extreme climate with 
maximum range of temperature. 
Question 6. 
State the pattern of temperature in mid latitudes. 
Answer: 
Due to spherical shape of the earth, temperature zone gets less insolation resulting in 
moderate climate with normal temperature ranging from 15°C to 30°C. The duration of 
sunshine is greater in summer than winter. So the summer is warm and winter is cold. 
Question 7. 
How would the breezes that blow during the day and those that blow during the night 
affect the temperature of a place situated in the coastal region ? 
Answer: 
During the day the sea breeze blowing from sea towards land keeps the coastal region 
cool and during the night land breeze blowing from land towards sea makes the sea 
cooler. This interchange of breeze maintains the heat balance resulting in the mild 
climate of the coastal regions with lower daily and annual ranges of temperature. 
Question 8. 
What difference is there in the temperatures on a mountain and on a sea shore ? 
Answer: 
The rate of decrease of temperature is 1°C for every 166 metres, the temperatures on a 
mountain are for lesser than the temperatures on a sea shore which is nearly at zero 
height. 
Question 9. 
Why is India cooler in December than in July ? 
Answer: 
Tropic of Cancer passes midway across India, so, there is summer season in July, while 
in December the sun is vertical on the Tropic of Capricorn in southern hemisphere, so 
India experiences winter season. So naturally December is cooler than July. 
Question 10. 
State two chief characteristics of the Temperate zone. 
Answer: 
Medium temperature and medium rainfall due to slanting rays of the sun and less 
evaporation. 
Question 11. 
Explain the following: 
(a) Diurnal range of temperature. 
(b) Mean Monthly Range of Temperature. 
(c) Mean Annual Range of Temperature. 
Answer: 
(a) Diurnal range is the difference between the maximum and minimum temperature 
within 24 hours, of the day. 
(b) It is the difference between the mean maximum and mean minimum temperatures 
within the month. 
(c) It is the difference between mean maximum and mean minimum temperatures within 
a year, mainly between June and January. 
Question 12. 
Define briefly ‘Heat Balance”. 
Answer: 
Heat balance is defined as the state of equilibrium that exists on earth between 
incoming insolation from the sun and the out going terrestrial radiation from the earth. 
Question 13. 
Name the heat zones of the earth. 
Answer: 
Torrid zone, Temperate zone and Frigid zone. 
II. Distinguish between each of the following 
Answer: 
Insolation and Terrestrial Radiation. 
Insolation : 
1. It is the incoming solar radiation intercepted by the earth. 
2. It travels in short waves. 
3. Insolation involves only 51 units out of 100 units of solar radiation. 
Terrestrial Radiation : 
1. It is the earth’s radiation given back to atmosphere and space. 
2. It travels in long waves. 
3. Out of 51 units of insolation 34 units are transferred to the atmosphere and 17 
units go back to space. 
Page 4


Insolation 
Exercises 
I. Short Answer Questions. 
Question 1. 
What is solar radiation ? What is its significance for the earth ? 
Answer: 
The sun continuously radiates heat and light energy in all the directions. It is known as 
solar radiation. Solar radiation is the only primary source of light and heat on the earth. 
The earth receives its heat from solar radiation which is a tiny fraction of the radiated 
energy of the sun. 
Question 2. 
What is meant by insolation ? State two of its main characteristics. 
Answer: 
The amount of solar energy received by the earth is called insolation, but only one part 
out of two billion parts reaches the earth. So, out of total 100% solar energy only 51% 
reaches the earth, 35% reflected back to into space and only 14% is absorbed by the 
ozone layer. 
Question 3. 
State two advantages of convectional heating of the atmosphere. 
Answer: 
Convectional heating of the atmosphere is done by heating up the layer of air touching 
land surface and rising up to warm up the upper layer, while the cold wind sinks down 
and again heated up by the terrestrial radiation. This circulation causes formation of 
clouds, rainfall and mild changes in climatic behaviour. 
Question 4. 
Name four factors that affect the temperature of a place. 
Answer: 
The four factors that affect the temperature of a place are : 
1. Latitude 
2. Distance from the sea. 
3. Altitude 
4. Wind direction 
5. Natural vegetation 
 
Question 5. 
How does the distance from the sea affect the distribution of temperature ? 
Answer: 
Due to the physical property of water, which is heated up and cooled down slowly with 
respect to the land. So, the coastal areas experience mild climate with least range of 
temperature, while the regions far from the sea are affected by extreme climate with 
maximum range of temperature. 
Question 6. 
State the pattern of temperature in mid latitudes. 
Answer: 
Due to spherical shape of the earth, temperature zone gets less insolation resulting in 
moderate climate with normal temperature ranging from 15°C to 30°C. The duration of 
sunshine is greater in summer than winter. So the summer is warm and winter is cold. 
Question 7. 
How would the breezes that blow during the day and those that blow during the night 
affect the temperature of a place situated in the coastal region ? 
Answer: 
During the day the sea breeze blowing from sea towards land keeps the coastal region 
cool and during the night land breeze blowing from land towards sea makes the sea 
cooler. This interchange of breeze maintains the heat balance resulting in the mild 
climate of the coastal regions with lower daily and annual ranges of temperature. 
Question 8. 
What difference is there in the temperatures on a mountain and on a sea shore ? 
Answer: 
The rate of decrease of temperature is 1°C for every 166 metres, the temperatures on a 
mountain are for lesser than the temperatures on a sea shore which is nearly at zero 
height. 
Question 9. 
Why is India cooler in December than in July ? 
Answer: 
Tropic of Cancer passes midway across India, so, there is summer season in July, while 
in December the sun is vertical on the Tropic of Capricorn in southern hemisphere, so 
India experiences winter season. So naturally December is cooler than July. 
Question 10. 
State two chief characteristics of the Temperate zone. 
Answer: 
Medium temperature and medium rainfall due to slanting rays of the sun and less 
evaporation. 
Question 11. 
Explain the following: 
(a) Diurnal range of temperature. 
(b) Mean Monthly Range of Temperature. 
(c) Mean Annual Range of Temperature. 
Answer: 
(a) Diurnal range is the difference between the maximum and minimum temperature 
within 24 hours, of the day. 
(b) It is the difference between the mean maximum and mean minimum temperatures 
within the month. 
(c) It is the difference between mean maximum and mean minimum temperatures within 
a year, mainly between June and January. 
Question 12. 
Define briefly ‘Heat Balance”. 
Answer: 
Heat balance is defined as the state of equilibrium that exists on earth between 
incoming insolation from the sun and the out going terrestrial radiation from the earth. 
Question 13. 
Name the heat zones of the earth. 
Answer: 
Torrid zone, Temperate zone and Frigid zone. 
II. Distinguish between each of the following 
Answer: 
Insolation and Terrestrial Radiation. 
Insolation : 
1. It is the incoming solar radiation intercepted by the earth. 
2. It travels in short waves. 
3. Insolation involves only 51 units out of 100 units of solar radiation. 
Terrestrial Radiation : 
1. It is the earth’s radiation given back to atmosphere and space. 
2. It travels in long waves. 
3. Out of 51 units of insolation 34 units are transferred to the atmosphere and 17 
units go back to space. 
Question 2. 
Land Breeze and Sea Breeze. 
Answer: 
Land Breeze : 
1. It blows from Land to sea. 
2. It blows at night. 
3. It makes the sea water cooler. 
4. It moderates the temperature of sea. 
Sea Breeze : 
1. It blows from sea to land. 
2. It blows in the day time. 
3. It makes coastal parts warmer 
4. It moderates the climate of the coastal parts. 
Question 3. 
Torrid and Temperate Zones. 
Answer: 
Torrid Zone : 
1. It lies between 23 1/2° N and 23 1/2° S 
2. It receives highest temperature and rainfall. 
3. It receives the vertical sun’s rays. 
4. Equatorial region and the tropical belt receive maximum insolatioa 
Temperate Zone : 
1. It lies between 23 1/2° N and 66 1/2° N & 23 1/2° S and 66 1/2° S 
2. It receives medium, temperature and rainfall. 
3. It received slanting rays of sun. 
4. Due to spherical shape of the earth, this zone received quite less amount of 
insolation. 
Question 4. 
Annual Range and Monthly Range of Temperature. 
Answer: 
Annual Range of Temperature : 
1. It is the difference between the highest and lowest temperatures within one year. 
2. It is the difference between the highest temperature of May-June and lowest 
temperature in December January, i.e. the temperature difference between 
summer and winter. 
Page 5


Insolation 
Exercises 
I. Short Answer Questions. 
Question 1. 
What is solar radiation ? What is its significance for the earth ? 
Answer: 
The sun continuously radiates heat and light energy in all the directions. It is known as 
solar radiation. Solar radiation is the only primary source of light and heat on the earth. 
The earth receives its heat from solar radiation which is a tiny fraction of the radiated 
energy of the sun. 
Question 2. 
What is meant by insolation ? State two of its main characteristics. 
Answer: 
The amount of solar energy received by the earth is called insolation, but only one part 
out of two billion parts reaches the earth. So, out of total 100% solar energy only 51% 
reaches the earth, 35% reflected back to into space and only 14% is absorbed by the 
ozone layer. 
Question 3. 
State two advantages of convectional heating of the atmosphere. 
Answer: 
Convectional heating of the atmosphere is done by heating up the layer of air touching 
land surface and rising up to warm up the upper layer, while the cold wind sinks down 
and again heated up by the terrestrial radiation. This circulation causes formation of 
clouds, rainfall and mild changes in climatic behaviour. 
Question 4. 
Name four factors that affect the temperature of a place. 
Answer: 
The four factors that affect the temperature of a place are : 
1. Latitude 
2. Distance from the sea. 
3. Altitude 
4. Wind direction 
5. Natural vegetation 
 
Question 5. 
How does the distance from the sea affect the distribution of temperature ? 
Answer: 
Due to the physical property of water, which is heated up and cooled down slowly with 
respect to the land. So, the coastal areas experience mild climate with least range of 
temperature, while the regions far from the sea are affected by extreme climate with 
maximum range of temperature. 
Question 6. 
State the pattern of temperature in mid latitudes. 
Answer: 
Due to spherical shape of the earth, temperature zone gets less insolation resulting in 
moderate climate with normal temperature ranging from 15°C to 30°C. The duration of 
sunshine is greater in summer than winter. So the summer is warm and winter is cold. 
Question 7. 
How would the breezes that blow during the day and those that blow during the night 
affect the temperature of a place situated in the coastal region ? 
Answer: 
During the day the sea breeze blowing from sea towards land keeps the coastal region 
cool and during the night land breeze blowing from land towards sea makes the sea 
cooler. This interchange of breeze maintains the heat balance resulting in the mild 
climate of the coastal regions with lower daily and annual ranges of temperature. 
Question 8. 
What difference is there in the temperatures on a mountain and on a sea shore ? 
Answer: 
The rate of decrease of temperature is 1°C for every 166 metres, the temperatures on a 
mountain are for lesser than the temperatures on a sea shore which is nearly at zero 
height. 
Question 9. 
Why is India cooler in December than in July ? 
Answer: 
Tropic of Cancer passes midway across India, so, there is summer season in July, while 
in December the sun is vertical on the Tropic of Capricorn in southern hemisphere, so 
India experiences winter season. So naturally December is cooler than July. 
Question 10. 
State two chief characteristics of the Temperate zone. 
Answer: 
Medium temperature and medium rainfall due to slanting rays of the sun and less 
evaporation. 
Question 11. 
Explain the following: 
(a) Diurnal range of temperature. 
(b) Mean Monthly Range of Temperature. 
(c) Mean Annual Range of Temperature. 
Answer: 
(a) Diurnal range is the difference between the maximum and minimum temperature 
within 24 hours, of the day. 
(b) It is the difference between the mean maximum and mean minimum temperatures 
within the month. 
(c) It is the difference between mean maximum and mean minimum temperatures within 
a year, mainly between June and January. 
Question 12. 
Define briefly ‘Heat Balance”. 
Answer: 
Heat balance is defined as the state of equilibrium that exists on earth between 
incoming insolation from the sun and the out going terrestrial radiation from the earth. 
Question 13. 
Name the heat zones of the earth. 
Answer: 
Torrid zone, Temperate zone and Frigid zone. 
II. Distinguish between each of the following 
Answer: 
Insolation and Terrestrial Radiation. 
Insolation : 
1. It is the incoming solar radiation intercepted by the earth. 
2. It travels in short waves. 
3. Insolation involves only 51 units out of 100 units of solar radiation. 
Terrestrial Radiation : 
1. It is the earth’s radiation given back to atmosphere and space. 
2. It travels in long waves. 
3. Out of 51 units of insolation 34 units are transferred to the atmosphere and 17 
units go back to space. 
Question 2. 
Land Breeze and Sea Breeze. 
Answer: 
Land Breeze : 
1. It blows from Land to sea. 
2. It blows at night. 
3. It makes the sea water cooler. 
4. It moderates the temperature of sea. 
Sea Breeze : 
1. It blows from sea to land. 
2. It blows in the day time. 
3. It makes coastal parts warmer 
4. It moderates the climate of the coastal parts. 
Question 3. 
Torrid and Temperate Zones. 
Answer: 
Torrid Zone : 
1. It lies between 23 1/2° N and 23 1/2° S 
2. It receives highest temperature and rainfall. 
3. It receives the vertical sun’s rays. 
4. Equatorial region and the tropical belt receive maximum insolatioa 
Temperate Zone : 
1. It lies between 23 1/2° N and 66 1/2° N & 23 1/2° S and 66 1/2° S 
2. It receives medium, temperature and rainfall. 
3. It received slanting rays of sun. 
4. Due to spherical shape of the earth, this zone received quite less amount of 
insolation. 
Question 4. 
Annual Range and Monthly Range of Temperature. 
Answer: 
Annual Range of Temperature : 
1. It is the difference between the highest and lowest temperatures within one year. 
2. It is the difference between the highest temperature of May-June and lowest 
temperature in December January, i.e. the temperature difference between 
summer and winter. 
Monthly range of Temperature : 
1. It is the difference between the maximum and minimum temperatures within a 
month. 
2. Mostly the middle of month is noted for maximum and end of the month records 
minimum temperatures. 
III. Give reasons for each of the following 
Question 1. 
North India has a greater range of temperature than South India. 
Answer: 
North India comes in temperate zone, while South India comes in Torrid Zone situated 
in the North and South of Tropic of Cancer. So North Indian places have greater range, 
which is greatest in the Desert of Rajasthan. 
Question 2. 
The temperature of Delhi is less than that of Chennai in December. 
Answer: 
Delhi is far from sea, while Chennai is situated along the coast of Bay of Bengal. So 
Delhi is colder than Chennai in December. 
Question 3. 
Distance from the sea affects the temperature of a place. 
Answer: 
Warm effect of sea keeps the temperature less in summer and higher in winter, e.g. 
Bombay (Mumbai) is wanner than Delhi in winter. 
Question 4. 
Land is heated and cooled faster than the sea. 
Answer: 
In the desert of Rajasthan range of temperature is highest due to the physical property 
of land to be heated and cooled down quickly with respect to the sea. So, the 
temperature difference is least at Mangalore and Chennai. 
Question 5. 
The temperature of a place depends largely upon its latitude. 
Answer: 
As the rays of the sun become more and more slanting with increasing latitudes. So the 
tropical region never gets snowfall, while the polar region is always frozen.