Insolation

Choose the correct option

Question 1

The sun continuously radiates heat and light energy in all the directions known as:

1. Energy radiation
2. Solar radiation
3. Sun radiation
4. Heat and light radiation

Answer

Solar radiation

Question 2

The amount of solar energy received by the earth is called:

1. Radiation
2. Insolation
3. Greenhouse radiation
4. Precipitation radiation

Answer

Insolation

Question 3

The heat radiated by the earth in the form of long waves is called:

1. Terrestrial radiation
2. Heat balance
3. Conduction
4. Convection

Answer

Terrestrial radiation

Question 4

When both incoming radiation and outgoing radiation are balanced, it is called:

1. Convection
2. Terrestrial radiation
3. Heat balance
4. Conduction

Answer

Heat balance

Question 5

Conduction : ................ :: Convection : ................

1. direct contact; circulatory motion
2. circulatory motion, direct contact
3. absorption, transference
4. transference, absorption

Answer

direct contact; circulatory motion

Question 6

The height of a place above the mean sea level:

1. Latitude
2. Altitude
3. Height
4. Sea level height

Answer

Altitude

Question 7

land : ............... :: water : ................

1. circulation, convection
2. currents, breeze
3. conduction , convection
4. circulation, circumvention

Answer

conduction , convection

Question 8

Sea breeze : daytime :: land breeze : ................

1. daytime
2. night time
3. dawn
4. dusk

Answer

night time

Question 9

The increase in temperature in valleys:

1. Mountain breeze
2. Normal Lapse Rate
3. Inversion of current
4. Valley Breeze

Answer

Valley Breeze

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.

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.

Two main characteristics of insolation are-

1. The Sun's energy reaches the Earth as short wave rays.
2. Out of the total 100% solar energy, only 51% reaches the Earth, 35% is reflected back into space and only 14% is absorbed by the atmospheric layers including the ozone during insolation.

Question 3

State two advantages of convectional heating of the atmosphere.

Answer

Two advantages of convectional heating of the atmosphere are-

1. Convection currents in the atmosphere cause sea breeze. During the day, the air over land becomes warmer and rises. Cool air from oceans moves in to take its place causing sea breeze.
2. At night, land breeze happens due to the opposite of this. Land surface gets cooled more quickly than the ocean surface. Air over land flows towards the ocean causing land breeze.

Question 4

Name four factors that affect the temperature of a place.

Answer

Four factors that affect the temperature of a place are-

1. Latitude of a place
2. Altitude of a place
3. Distance from the sea
4. Slope of the land

Question 5

State the pattern of temperature in mid latitudes.

Answer

Due to spherical shape of the Earth, mid latitudes get 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 6

What difference is there in the temperatures on a mountain and on a sea shore?

Answer

Temperature keeps on decreasing with increase in altitude. There is a fall of 1°C in temperature on climbing every 166 metres. Hence, the temperature on a mountain is lower than the temperature on a sea shore.

Question 7

Why is India cooler in December than in July?

Answer

The Tropic of Cancer passes mid-way across India. On June 21, the rays of the Sun falls directly over the Tropic of Cancer as the North Pole get tilted towards the Sun. The southern hemisphere is tilted away from the Sun during this time. Hence, July is hot.

On December 22nd, the Southern Hemisphere is tilted towards the Sun and the Sun rays fall vertically over the Tropic of Capricorn, while the Northern Hemisphere is tilted away from the Sun. So, India, which lies in the Northern Hemisphere experience winters in December.

Distinguish between each of the following

Question 1

Insolation and Terrestrial Radiation

Answer

Question 2

Land breeze and sea breeze

Answer

Structured Questions

Question 1(a)

How is 'heat balance' achieved?

Answer

The atmosphere absorbs 34 units of the Earth's radiation, but it absorbs only 14 units of the Sun's incoming radiation. Thus, the atmosphere is heated more by terrestrial radiation given out by the Earth than by the incoming insolation from the Sun.

At night, the atmosphere acts as a greenhouse and keeps the Earth's surface warm by preventing the terrestrial radiation from escaping into space. During the day, the atmosphere absorbs 14% of insolation and thus regulates temperature on Earth.

Question 1(b)

State how latitude affects the temperature of a place.

Answer

The temperature of a place depends on the latitude of a place as temperature decreases with increase in latitude on either side of the equator due to the spherical shape of the Earth and its annual revolution around the Sun.

Also, the mid day Sun is almost overhead within the tropics but at oblique angles outside the tropics.

Question 1(c)

Give a reason for each of the following:

(i) North India has a greater range of temperature than South India.

(ii) The temperature of Delhi is less than that of Chennai in December.

(iii) Desert areas experience a high day temperature and a much lower night temperature.

Answer

(i) North India lies away from the water bodies and experiences continental type of climate whereas South India being near the water bodies experiences maritime climate. Also, North India comes in temperate zone as it lies towards the north of Tropic of Cancer whereas South India falls in Torrid Zone towards the south of Tropic of Cancer. Due to these reasons, North India has a greater range of temperature than South India.

(ii) The temperature of Delhi is less than that of Chennai in December because Delhi lies beyond the Tropic of Cancer, in the Temperate zone. So in December, it receives slanting rays of the sun. But Chennai is located in Torrid zone and hence, it receives vertical rays of the sun throughout the year. Therefore, the temperature of Delhi is lesser during the December.

(iii) Desert areas experience a high day temperature and a much lower night temperature because desert areas are covered with sand. The physical property of the sand is to get heated up quickly and cool down abruptly. So, the day temperature is very high and the night temperature is very low.

Question 1(d)

Draw a well labelled diagram to show the Heat Budget of the Earth.

Answer

Below labelled diagram shows the Heat Budget of the Earth:

Question 2(a)

State the five temperature zones of the Earth.

Answer

The five temperature zones of the Earth are-

1. Torrid Zone
2. North Temperate Zone
3. South Temperate Zone
4. North Frigid Zone
5. South Frigid Zone

Question 2(b)

Explain the Normal Lapse Rate.

Answer

The rate of decrease of temperature with height is about 6°C per km above the sea level, so on climbing every 166 metres, there is a fall of 1°C in temperature. It is known as Normal Lapse Rate.

Question 2(c)

Give a reason for each of the following:

(i) Distance from the sea affects the temperature of a place.

(ii) Land is heated and cooled faster than the sea.

(iii) The ports of the western coast of Europe remain ice-free during winter.

Answer

(i) Distance from the sea affects the temperature of a place as the sea breeze blowing from the sea towards the land cools the coastal regions during the day. At night, the land breeze makes the sea cooler. This interchange of breeze maintains the heat balance. Hence, the areas close to the sea have a lower daily and annual ranges of temperatures and enjoy a moderate climate than the areas lying in the interior.

(ii) Land is heated and cooled faster than the sea because water is mobile and the warm water mixes easily with the cold water and is neither heated nor cooled quickly. On the other hand, the Sun's rays heat a piece of land more rapidly because unlike water, the heat obtained by the area remains confined to that area and does not mix with other areas of land.

(iii) The ports of the western coast of Europe remain ice-free during winter due to the warm effect of the Gulf Stream and North Atlantic Drift.

Question 2(d)

Draw a well labelled diagram showing that the vertical rays are hotter than slanting rays.

Answer

Below labelled diagram shows that the vertical rays are hotter than slanting rays:

Question 3(a)

How does the distance from the sea affect the distribution of temperature?

Answer

Distance from the sea affects the temperature of a place as the sea breeze blowing from the sea towards the land cools the coastal regions during the day. At night, the land breeze makes the sea cooler. This interchange of breeze maintains the heat balance. Hence, the areas close to the sea have a lower daily and annual ranges of temperatures and enjoy a moderate climate than the areas lying in the interior.

Question 3(b)

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 towards the land from the sea keeps the coastal region cool and during the night the land breeze blowing from the land towards the sea makes the sea cooler.

This interchange of breeze maintains the heat balance. Hence, the areas close to the sea have a lower daily and annual ranges of temperatures and enjoy a moderate climate than the areas lying in the interior.

Question 3(c)

Give a reason for each of the following:

(i) Higher the latitude, lower is the temperature.

(ii) The vertical rays of the Sun give more insolation than the slanting rays.

(iii) A desert region has a high range of temperature than a forest region.

Answer

(i) At higher latitudes, the rays of the Sun fall in an oblique way. Oblique rays not only travel a longer distance, but also heat a larger area. Thus, they have less heating power. Hence, with higher latitudes, the temperature goes on decreasing.

(ii) The vertical rays of the Sun give more insolation than the slanting rays because vertical rays travel a shorter distance and heat up a smaller surface area leading to higher temperatures whereas slanting rays not only travel a longer distance, but also heat a larger area. Thus, they have less heating power.

(iii) Hot deserts have no cloud cover, which allows high insolation during the day and rapid loss of heat due to terrestrial radiation at night resulting in high range of temperature. On the other hand, forests absorb 90% insolation and the solar energy absorbed by plants is used in the process of transpiration resulting in low range of temperature.

Question 3(d)

Draw a well labelled diagram to show the land and sea breeze.

Answer

Below labelled diagram shows the land and sea breeze:

Thinking Skills

Question 1

Solar radiation is the only primary source of light and heat on the earth. But only 51% of solar energy reaches the earth. What would happen if the entire solar energy reaches the earth? Give reasons to support your answer.

Answer

If the entire solar energy were to reach the Earth instead of just 51%, there would be several significant consequences. Here are some reasons to support this answer:

1. Increased Temperature — The Earth's surface would experience a significant increase in temperature. The additional solar energy would lead to a substantial rise in average global temperatures, resulting in hotter climates worldwide. This increase in temperature could have far-reaching effects on ecosystems, weather patterns, and human habitats.
2. Ecosystem Disruption — The increased solar energy would disrupt ecosystems and ecological balances. Many species have evolved to adapt to the existing amount of solar radiation. A sudden influx of additional energy could lead to shifts in vegetation patterns, changes in animal behavior and migration patterns, and the disruption of delicate ecological relationships.
3. Water Cycle Changes — The increased solar energy would accelerate the water cycle. Higher temperatures would lead to increased evaporation rates, which would result in more moisture in the atmosphere. This, in turn, could intensify precipitation, leading to more frequent and intense rainfall, storms, and even extreme weather events like hurricanes.
4. Impact on Human Health — The amplified solar radiation could have adverse effects on human health. Increased exposure to ultraviolet (UV) radiation could lead to a higher incidence of skin cancer, cataracts, and other UV-related health issues. It would necessitate enhanced sun protection measures and a heightened risk awareness.
5. Energy Overload — The Earth's energy systems would face challenges in handling the excess solar energy. Our current energy infrastructure is designed to accommodate the amount of solar energy that reaches the Earth. If the energy input were to increase drastically, it could strain power grids, transmission lines, and other energy-related infrastructure, requiring significant upgrades and modifications.
6. Climate Instability — The sudden influx of solar energy would disrupt the delicate balance of Earth's climate system. It could potentially trigger feedback loops that amplify the warming effect, leading to a runaway greenhouse effect. This could result in further temperature increases, exacerbating climate change and its associated consequences.

Question 2

Do you think Greenhouse Gases affect earth's heat budget? Give examples to support your answer.

Answer

Yes, Greenhouse Gases affect the Earth's heat budget as can be understood by the following examples:

1. Greenhouse Effect — Greenhouse gases, such as carbon dioxide (CO₂) and methane (CH₄), trap heat from the sun, preventing it from escaping back into space.
2. Increased Temperatures — The presence of greenhouse gases in the atmosphere leads to an increase in average global temperatures, contributing to global warming.
3. Climate Change — The buildup of greenhouse gases alters the balance of the Earth's heat budget, resulting in changes in climate patterns, including temperature shifts and extreme weather events.
4. Human Activities — Human activities, like burning fossil fuels and deforestation, release large amounts of greenhouse gases into the atmosphere, intensifying the greenhouse effect and impacting the Earth's heat budget.