Worksheet Solutions: Solar Radiation, Heat Balance and Temperature | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks

Q1: The energy received by the Earth from the sun is known as _______________.
Ans: insolation.
Insolation stands for Incoming Solar Radiation. It represents the energy the Earth receives from the sun.

Q2: The Earth is farthest from the sun on 4th July, a position called _______________.
Ans: aphelion.
Aphelion is the point in the Earth's orbit when it is farthest from the sun, occurring in early July.

Q3: The angle of inclination of the sun's rays is determined by the _______________ of a place.
Ans: latitude.
The angle of inclination of the sun's rays varies with latitude, affecting the intensity of solar radiation.

Q4: The red color of the rising and setting sun is a result of _______________ within the atmosphere.
Ans: scattering of light.
The scattering of shorter wavelengths of light (blue and violet) in the atmosphere leaves red and orange colors visible during sunrise and sunset.

Q5: The process by which the Earth's surface is heated from below and radiates heat to the atmosphere is called _______________.
Ans: terrestrial radiation.
Terrestrial radiation is the long-wave radiation emitted by the Earth's surface, warming the atmosphere from below.

Q6: The variation in the net heat budget at the Earth's surface results in some areas having a _______________ radiation balance.
Ans: surplus.
In areas with surplus radiation balance, the Earth receives more heat from the sun than it loses through terrestrial radiation.

Q7: The temperature generally decreases with increasing height at a rate of _______________ per 1,000 meters.
Ans: 6.5°C.
This is known as the normal lapse rate, and it signifies the rate at which temperature drops as you gain altitude in the troposphere.

Q8: The presence of warm ocean currents can lead to _______________ temperatures in coastal areas.
Ans: higher.
Warm ocean currents can transfer heat to coastal regions, moderating temperatures and making them higher than inland areas.

Q9: Inversion of temperature can occur when the Earth's surface is _______________ than the air above during the night.
Ans: cooler.
Temperature inversion occurs when a layer of cold air is trapped beneath a layer of warmer air, often happening during clear, calm nights.

Q10: The global distribution of temperature can be observed by studying the distribution of _______________.
Ans: isotherms.
Isotherms are lines connecting areas with the same temperature, helping us understand temperature patterns worldwide.

Assertion and Reason Based

Q1: Assertion: The Earth receives most of its energy in short wavelengths.
Reason: Short wavelengths are more effective at heating the Earth's surface.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (b)
While the assertion is true, the reason doesn't explain why short wavelengths are more effective. Short wavelengths are more effective because they carry more energy, not just because they are short.

Q2: Assertion: The Earth's atmosphere is largely transparent to short-wave solar radiation.
Reason: Water vapor, ozone, and other gases in the atmosphere absorb much of the near infrared radiation.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
The assertion is correct, and the reason explains why short-wave radiation is transmitted through the atmosphere, while some longer wavelengths are absorbed by specific gases.

Q3: Assertion: The Earth's temperature generally decreases with increasing height.
Reason: The atmosphere is indirectly heated by terrestrial radiation from below.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
The assertion is true, and the reason correctly explains that the atmosphere's temperature decreases with height due to terrestrial radiation from the Earth's surface.

Q4: Assertion: The presence of warm ocean currents can lead to higher temperatures in coastal areas.
Reason: Land heats up and cools down quickly compared to the sea.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
Both the assertion and reason are true. Warm ocean currents can moderate coastal temperatures, and land does heat and cool more rapidly than the sea.

Q5: Assertion: Inversion of temperature is more common during the daytime.
Reason: Inversion occurs when the Earth's surface is cooler than the air above.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (b)
Inversion is more common during the night when the Earth's surface cools rapidly. The assertion is true, but the reason is not the correct explanation for its occurrence.

Very Short Answer Type Questions

Q1: What is insolation?
Ans: Insolation stands for Incoming Solar Radiation, which is the energy received by the Earth from the sun.

Q2: What is aphelion?
Ans: Aphelion is the position in the Earth's orbit when it is farthest from the sun, occurring around 4th July.

Q3: What is perihelion?
Ans: Perihelion is the position in the Earth's orbit when it is nearest to the sun, around 3rd January.

Q4: How does the Earth's axis inclination affect insolation at different latitudes?
Ans: The angle of inclination of the sun's rays varies with latitude, affecting the intensity of solar radiation.

Q5: Why does the atmosphere appear blue during the day?
Ans: The red color of the rising and setting sun is a result of shorter wavelengths (blue and violet) being scattered in the atmosphere.

Q6: What are isotherms?
Ans: Isotherms are lines connecting areas with the same temperature, helping analyze global temperature distribution.

Q7: Explain convection as a method of heating the atmosphere.
Ans: Convection is the process of heat transfer in the atmosphere through the vertical movement of air parcels. As warm air rises, it transfers heat to the surrounding cooler air, leading to the heating of the atmosphere.

Q8: What are air masses and how do they affect temperature?
Ans: Air masses are large bodies of air with similar temperature and humidity characteristics. When air masses move over a region, they can bring changes in temperature depending on their origin and properties.

Q9: What is the normal lapse rate for temperature?
Ans: The normal lapse rate represents the rate at which temperature decreases with increasing height in the troposphere. It is approximately 6.5°C per kilometer.

Q10: What is the moderating influence of the sea on temperature?
Ans: Warm ocean currents can lead to higher temperatures in coastal areas due to their moderating influence. The ocean acts as a heat sink, absorbing and releasing heat slowly, which helps stabilize the temperature in coastal regions.

Short Answer Type Questions

Q1: Describe the process of terrestrial radiation.
Ans: Terrestrial radiation is the process by which the Earth's surface, heated by incoming solar radiation, emits long-wave radiation, warming the atmosphere from below. This is essential for maintaining the Earth's heat balance.

Q2: Explain the concept of the Earth's heat budget.
Ans: The Earth's heat budget is a balance between the incoming solar radiation (insolation) and the outgoing terrestrial radiation. If the incoming and outgoing radiation are in equilibrium, the Earth maintains a constant temperature. Any imbalance can lead to climate changes.

Q3: How does the presence of warm and cold ocean currents influence temperature?
Ans: Warm ocean currents can moderate coastal temperatures because they transfer heat from warmer regions to the coast. Cold ocean currents have the opposite effect, cooling coastal areas.

Q4: Discuss the distribution of temperature in the Northern and Southern Hemispheres in January.
Ans: In January, the Northern Hemisphere experiences temperature variations due to the influence of landmasses and warm ocean currents, leading to bending isotherms. In contrast, the Southern Hemisphere's temperature distribution is more gradual, with parallel isotherms.

Q5: Explain the phenomenon of inversion of temperature.
Ans: Temperature inversion occurs when a layer of cold air is trapped beneath a layer of warmer air. It is more common during the night when the Earth's surface cools rapidly, creating stable, calm conditions.

Q6: Describe the effects of the Earth's latitude on temperature.
Ans: The Earth's temperature varies with latitude because insolation is more direct at lower latitudes, leading to higher temperatures. At higher latitudes, the angle of incoming solar radiation is more oblique, resulting in cooler temperatures.

Q7: How does the altitude of a place affect its temperature?
Ans: Temperature decreases with increasing altitude due to the normal lapse rate. The atmosphere is indirectly heated from below by terrestrial radiation, so places at higher elevations are generally cooler.

Q8: What are the factors that control temperature distribution?
Ans: Temperature is influenced by latitude, altitude, distance from the sea, air-mass circulation, presence of warm and cold ocean currents, and local aspects. These factors contribute to the complex patterns of temperature distribution.

Long Answer Type Questions

Q1: Discuss the impact of solar radiation on the Earth's heat balance and temperature.
Ans: Impact of Solar Radiation on Earth's Heat Balance and Temperature:

• Solar radiation, or insolation, is the primary source of energy for the Earth.
• It heats the Earth's surface, driving weather patterns, ocean currents, and climate.
• The Earth's heat budget balances incoming solar radiation with outgoing terrestrial radiation.
• Any imbalance can lead to climate change, as seen in global warming.
• Solar radiation varies with latitude and is influenced by the Earth's axial tilt, resulting in seasonal temperature changes.

Q2: Explain the role of atmospheric gases in the passage of solar radiation and their effect on temperature.
Ans: Role of Atmospheric Gases and Their Effect on Temperature:

• The Earth's atmosphere is transparent to short-wave solar radiation.
• Water vapor, ozone, and other gases absorb some near-infrared radiation.
• This absorption warms the atmosphere and contributes to the greenhouse effect.
• Greenhouse gases like carbon dioxide further trap long-wave terrestrial radiation, maintaining Earth's temperature.
• An increase in greenhouse gases, such as through human activities, leads to global warming.

Q3: Describe the variations in insolation at the Earth's surface and the factors responsible for these variations.
Ans: Variations in Insolation and Their Causes:

• Insolation varies during a day, season, and year due to several factors.
• Factors include Earth's rotation, the angle of the sun's rays, length of the day, transparency of the atmosphere, and land configuration.
• The Earth's axial tilt plays a significant role in changing day length and insolation at different latitudes.
• Latitude affects the angle of sunlight and, therefore, the intensity of insolation.
• Land configuration and transparency of the atmosphere have lesser effects on insolation variations.

Q4: Analyze the global distribution of temperature and the factors that influence it.
Ans: Global Distribution of Temperature and Influencing Factors:

• Temperature distribution is influenced by latitude, altitude, distance from the sea, air-mass circulation, ocean currents, and local aspects.
• Latitude affects insolation and, in turn, temperature; higher latitudes receive less direct sunlight.
• Altitude leads to temperature changes, with a decrease of approximately 6.5°C per 1,000 meters.
• Proximity to the sea moderates temperature, as water heats and cools more slowly than land.
• Warm and cold ocean currents influence coastal temperatures, as warm currents raise and cold currents lower temperatures.
• Air-mass circulation patterns can bring warm or cold air to a region, affecting temperature. Local aspects, like topography, also play a role.