RBSE Solutions Class 11 Physical Geography Chapter 12 Insolation and Heat Budget

RBSE Class 11 Physical Geography Chapter 12 Multiple Choice Questions

 

Question 1. The insolation is measured by an instrument called:
(a) Pyroheliometer
(b) Thermometer
(c) Barometer
(d) Centimeter
Answer: (a) Pyroheliometer
In simple words: The amount of solar radiation that reaches the Earth's surface is measured using a special tool called a pyroheliometer. This helps scientists understand how much sunlight our planet receives.

🎯 Exam Tip: Remember specific instruments for different measurements in geography; they are often asked in MCQs. Pyroheliometer measures direct solar radiation.

 

Question 2. How many minutes do sun's rays take to reach the earth?
(a) 1 minute
(b) 4 minutes
(c) 8 minutes
(d) 16 minutes
Answer: (c) 8 minutes
In simple words: It takes about 8 minutes for sunlight to travel from the Sun to Earth. Light travels very fast, but the distance is huge, so it still takes some time.

🎯 Exam Tip: Know key astronomical facts like the speed of light and travel times of radiation from the Sun to Earth.

 

Question 3. The solar energy coming to Earth is called:
(a) Terrestrial radiation
(b) Solar radiation
(c) Insolation
(d) Heat budget
Answer: (c) Insolation
In simple words: The energy we get from the Sun on Earth is called insolation. It is crucial for heating our planet and supporting life.

🎯 Exam Tip: Differentiate between "solar radiation" (general energy from the sun) and "insolation" (solar radiation received at Earth's surface).

 

Question 4. The meaning of inversion of temperature is:
(a) Increase of temperature on the surface
(b) Uneven fall in temperature
(c) Temperature rise along with height
(d) Temperature decrease along with height
Answer: (c) Temperature rise along with height
In simple words: Usually, the air gets colder as you go higher up. But sometimes, when there is a temperature inversion, the air gets warmer instead of colder as you go up. This can trap pollution close to the ground.

🎯 Exam Tip: Temperature inversion is a reversal of the normal temperature profile in the atmosphere, important for understanding local climate and pollution patterns.

 

Question 5. How much of the total solar radiation reaches on the earth?
(a) 51%
(b) 48%
(c) 35%
(d) 17%
Answer: (a) 51%
In simple words: Out of all the energy the Sun sends, about half of it actually reaches the Earth's surface. The rest is either reflected away or absorbed by the atmosphere before it gets here.

🎯 Exam Tip: Remember the Earth's energy budget percentages, especially the amount of insolation reaching the surface, as this is a fundamental concept.

RBSE Class 11 Physical Geography Chapter 12 Very Short Answer Type Questions

 

Question 1. What is solar radiation?
Answer: Solar radiation is the energy that is sent out from the surface of the Sun. This energy travels through space and is crucial for life on Earth. It includes various types of waves, such as visible light and ultraviolet rays.
In simple words: Solar radiation is the energy that comes from the Sun.

🎯 Exam Tip: When defining a term, use clear and concise language. Mentioning its source and nature (energy) helps score full marks.

 

Question 3. What is the distance of the earth from the sun?
Answer: The average distance between the Earth and the Sun is about 150 million kilometers (15 million kilometers, as given in the text). This distance changes slightly throughout the year because Earth's orbit is not a perfect circle.
In simple words: Earth is usually about 15 million kilometers away from the Sun.

🎯 Exam Tip: Be precise with numerical values. Note that "15 million kilometers" here is likely a simplified or specific measurement, while the more common figure is 150 million km.

 

Question 4. What is meant by arbitrariness?
Answer: Arbitrariness, in the context of temperature, means that the temperature is not the same everywhere on Earth's surface; it changes from place to place. This variation occurs due to different factors, leading to diverse climates globally.
In simple words: Arbitrariness means that temperature is different in various places on Earth.

🎯 Exam Tip: In geography, "arbitrariness" when applied to distribution usually refers to uneven or non-uniform spread.

 

Question 5. What is the main source of atmospheric heating?
Answer: The main source of heating for the Earth's atmosphere is the Sun. Solar energy, primarily in the form of shortwave radiation, warms the Earth's surface, which then radiates heat back into the atmosphere as longwave radiation, heating it from below.
In simple words: The Sun is the main source that heats our atmosphere.

🎯 Exam Tip: While the Sun is the ultimate source, clarify that the atmosphere is heated indirectly by the Earth's surface, not directly by solar rays.

RBSE Class 11 Physical Geography Chapter 12 Short Answer Type Questions

 

Question 1. What is meant by Earth's Albedo?
Answer: Earth's albedo refers to the amount of sunlight reflected back into space from the Earth's surface, compared to the total sunlight that hits it. When light rays strike any surface, some part is reflected according to reflection rules. The amount of light reflected depends on how smooth or bright the surface is. For instance, fresh snow has a high albedo, reflecting a lot of sunlight.
In simple words: Earth's albedo is how much sunlight the Earth reflects back into space.

🎯 Exam Tip: Explain that different surfaces have different albedo values (e.g., snow reflects more than dark soil) and how this impacts Earth's temperature.

 

Question 2. What is meant by inversion of temperature?
Answer: Normally, temperature decreases as you go higher in the troposphere, which is the lowest part of the atmosphere. However, in specific situations, temperature inversion occurs, meaning the temperature increases with elevation instead of decreasing. This happens because cooler, denser air gets trapped below warmer air. This phenomenon is often seen in valleys on cold, clear nights.
In simple words: Temperature inversion is when the air gets warmer as you go higher up, which is the opposite of what usually happens.

🎯 Exam Tip: When defining inversion of temperature, highlight the contrast with the normal lapse rate and mention common conditions where it occurs (e.g., clear nights, valleys).

 

Question 3. What is insolation?
Answer: The term insolation combines "sol" (Sun) and "in-ation" (coming in), referring to the solar radiation received by the Earth from the Sun. It is the solar energy that strikes the Earth's surface. However, not all the Sun's energy reaches the ground; only a very small fraction (about two billionths) of its total output actually reaches Earth.
In simple words: Insolation is the sunlight energy that reaches the Earth from the Sun.

🎯 Exam Tip: Emphasize that insolation is the *received* solar radiation, not just the radiation emitted by the sun, and note that only a fraction reaches Earth.

 

Question 4. What are the factors affecting insolation?
Answer: The amount of insolation received in an area changes based on weather and atmospheric conditions. The following factors influence the temperature from the Sun on the Earth's surface:
1. Distance from the equator: The Sun's rays hit the equator almost directly, but as you move towards the poles, the rays become slanted, reducing insolation.
2. Height above sea level: As altitude increases, the temperature generally decreases. This is why mountains are colder than plains.
3. Distance from the sea: Coastal areas have more stable temperatures, while inland areas experience greater temperature variations due to land heating and cooling faster than water.
4. Sea currents: Ocean currents, whether warm or cold, can significantly affect the temperature of nearby coastal regions.
5. Prevailing winds: Winds can increase or decrease temperature depending on whether they are cold or warm.
6. Slope of land: The angle at which land faces the Sun affects how much sunlight it receives, causing temperature variations on different slopes.
In simple words: Many things like how far a place is from the equator, its height, how close it is to the sea, ocean currents, winds, and land slopes change how much sunlight an area gets.

🎯 Exam Tip: When listing factors, provide a brief explanation for each to show a clear understanding of its impact on insolation.

 

Question 5. What is the difference between the horizontal and vertical distribution of temperature?
Answer: The distribution of temperature can be understood in two ways: horizontally and vertically.
Horizontal distribution of temperature: This refers to how temperature varies across different latitudes on the Earth's surface. It means looking at temperature changes from the equator towards the poles. On a map, these distributions are often shown using isotherms, which are lines connecting places of equal temperature. This distribution is mainly influenced by factors like latitude and land-sea differences.
Vertical distribution of temperature: This describes how temperature changes with altitude through the different layers of the atmosphere, starting from the Earth's surface. Generally, temperature decreases as you go higher up in the troposphere. However, this decrease is not the same everywhere and can be affected by local conditions, sometimes leading to temperature inversion where it temporarily increases with height.
In simple words: Horizontal temperature distribution shows how hot or cold it is across the Earth's surface (like from the equator to the poles), while vertical distribution shows how temperature changes as you go higher into the sky.

🎯 Exam Tip: Clearly define each type of distribution and mention the key factors influencing them (latitude for horizontal, altitude for vertical) to highlight the difference.

RBSE Class 11 Physical Geography Chapter 12 Essay Type Questions

 

Question 1. What is meant by insolation? Describe the factors affecting the distribution of temperature.
Answer: Insolation refers to the solar radiation that reaches the Earth from the Sun. It is the incoming sunlight energy that the Earth receives. The process of the Earth gaining this solar radiation is called the reception of insolation. The sunlight energy arriving at the surface is commonly known as insolation.
The distribution of temperature is not uniform across the Earth's surface, primarily due to varying weather and atmospheric conditions. The following factors contribute to this unequal distribution of temperature:
1. Distance from the Equator: Sun rays fall almost directly on the equator throughout the year, resulting in more sunlight. Moving towards the poles, the Sun's rays become slanted, providing less heat. This is why polar regions are very cold and covered in snow.
2. Distance from the Sea: Land heats up and cools down faster than water. Coastal areas experience more moderate and stable temperatures, while inland regions have greater temperature extremes.
3. Sea Currents: Both cold and warm ocean currents significantly affect the temperatures of nearby coastal areas. For example, the warm Gulf Stream keeps parts of Europe warmer.
4. Prevailing Winds: Winds can raise or lower temperatures depending on whether they are warm or cold in nature. Hot winds like the 'Sirocco' or 'Chinook' can increase temperatures, while cold winds can lower them.
5. Slope of Land: Slopes that face the Sun receive more direct sunlight and therefore have higher temperatures. Conversely, slopes facing away from the Sun are cooler. This is evident in mountain ranges like the Himalayas.
6. Nature of the Surface: Surfaces covered with snow or dense vegetation reflect most sunlight, keeping temperatures low. Areas with sand or dark soil absorb more insolation, leading to higher temperatures. This reflection process is called 'Albedo'.
7. Clouds and Rain: Cloudy areas often receive more rainfall. Clouds can reflect sunlight, preventing high temperatures, while clear areas allow more solar radiation to reach the surface.
8. Heat Budget: The Earth receives solar radiation as short waves. After interacting with the Earth, this heat is radiated back as long waves, known as Terrestrial Radiation. The balance between incoming solar radiation and outgoing terrestrial radiation is called the heat budget. Only a fraction (one part out of two billion) of the Sun's total energy reaches Earth. The rest is absorbed, reflected, or scattered by the atmosphere. A balanced heat budget ensures stable global temperatures, but human activities can affect this balance. The entire heat budget process can be illustrated by considering 100 units of incoming solar radiation, where about 51 units ultimately reach the Earth's surface (34 directly and 17 indirectly through atmospheric light), while 35 units are reflected or dispersed by clouds and the atmosphere (27 by clouds, 2 by surface, 6 by atmosphere) without heating the Earth, and 14 units are absorbed by the atmosphere. The Earth also radiates heat back, and maintaining a balance is key to temperature stability.
In simple words: Insolation is the sunlight Earth gets from the Sun. Many things like distance from the equator, proximity to the sea, ocean currents, winds, land slope, surface type (snowy or sandy), clouds, and the balance of incoming and outgoing heat (heat budget) all change how hot or cold different places on Earth are.

🎯 Exam Tip: For a comprehensive answer on factors affecting temperature, categorize them logically (e.g., latitudinal, altitudinal, land-sea differences, atmospheric conditions) and provide specific examples for each.

 

Question 3. Explaining the distribution of temperature, clarify horizontal and vertical distribution of temperature on the globe.
Answer: Temperature is not evenly spread across the Earth's surface, and its distribution is greatly influenced by latitude. The world can be divided into three main temperature zones based on this. Temperature distribution is closely linked to insolation and is mainly understood through two types: horizontal and vertical distribution.
1. Horizontal Distribution of Temperature: This refers to how temperature varies across different latitudes. Temperature changes as one moves from the equator towards the poles. On maps, these temperature distributions are shown using lines called isotherms, which connect places with the same average temperature. To analyze temperature patterns, the months of January and July are usually chosen because they show the minimum and maximum temperatures in most parts of the world.
    Isotherms of January: In January, the Sun's rays fall directly on the Tropic of Capricorn in the Southern Hemisphere, causing summer there and winter in the Northern Hemisphere. So, temperatures are higher in the Southern Hemisphere and lower in the Northern Hemisphere. The isotherms during this period show low temperatures in the Northern Hemisphere, with a -30°C isotherm found in parts of Siberia. Southern North America, Southern Europe, and South Asia typically see 10°C to 20°C isotherms.
    Isotherms of July: In July, the Sun's rays are almost directly over the Tropic of Cancer in the Northern Hemisphere, bringing summer to the Northern Hemisphere and winter to the Southern Hemisphere. Temperatures are highest in the inner parts of the Northern continents and tropical deserts, with approximately 27°C at the equator. In July, isotherms in the Northern Hemisphere become very skewed over land but remain mostly parallel to latitudes in the Southern Hemisphere. Areas like northern Siberia, Europe, and Alaska might have a 10°C isotherm, while Central Asia, northern Japan, southwestern Europe, and Canada commonly have 20°C. South Asia, northern Africa, and Mexico show 30°C isotherms. In the Southern Hemisphere, 20°C isotherms are found in Central Australia and South America, extending to 10°C in the southern parts of these continents. Antarctica, however, experiences minimal temperatures in July.
2. Vertical Distribution of Temperature: This describes how temperature changes at different altitudes through the atmosphere above the Earth's surface. Scientific evidence shows that temperature generally decreases as height increases. This is why hills and mountains are typically colder than plains. In the troposphere, temperature decreases by about 1°C for every 165 meters of ascent, a rate known as the normal lapse rate. This rate can vary due to seasons, local conditions, and turbulence. The temperature continues to decrease up to the troposphere's upper boundary, after which the rate of decrease stops or changes.
In simple words: Temperature is distributed horizontally (across the Earth, from equator to poles, shown by lines called isotherms) and vertically (from the ground upwards into the sky). Horizontal patterns change by season, like in January and July. Vertical patterns usually mean it gets colder as you go higher.

🎯 Exam Tip: When describing temperature distribution, always include the influence of latitude and altitude. For horizontal distribution, referencing isotherms and seasonal variations (January/July) is key.

RBSE Class 11 Physical Geography Chapter 12 Other Important Questions

RBSE Class 11 Physical Geography Chapter 12 Multiple Choice Questions

 

Question 1. What is the temperature of the surface of the Sun?
(a) 4000°C
(b) 5000°C
(c) 6000°C
(d) 7000°C
Answer: (c) 6000°C
In simple words: The surface of the Sun is extremely hot, with a temperature of around 6000 degrees Celsius. This intense heat is what generates the solar energy that reaches Earth.

🎯 Exam Tip: Knowing approximate temperatures of celestial bodies like the Sun is good general knowledge for geography.

 

Question 3. What is the main source of heat on the earth?
(a) Moon
(b) Sun
(c) Meteor
(d) Stars
Answer: (b) Sun
In simple words: The Sun is the primary source of all heat and energy on Earth. Without it, our planet would be a frozen, lifeless world.

🎯 Exam Tip: Always identify the Sun as the primary energy source for most Earth processes, including heat, light, and climate.

 

Question 4. Where is the most heat experienced?
(a) on the equator
(b) on the Tropic of Cancer
(c) on the Tropic of Capricorn
(d) on the Arctic Circle
Answer: (a) on the equator
In simple words: The area around the equator gets the most direct sunlight throughout the year. Because of this, it is generally the warmest region on Earth.

🎯 Exam Tip: Relate the amount of heat received to the angle of the sun's rays – direct rays mean more concentrated heat.

 

Question 5. Into how many heat zones is the earth divided?
(a) 2
(b) 3
(c) 4
(d) 5
Answer: (b) 3
In simple words: The Earth is divided into three main heat zones: the Torrid Zone (hot), the Temperate Zones (mild), and the Frigid Zones (cold). These zones are based on how much sunlight they receive.

🎯 Exam Tip: Clearly name and describe the characteristics of the three heat zones (Torrid, Temperate, Frigid) and their latitudinal extents.

 

Question 6. In the southern hemisphere, when do the rays of sun shine vertically on the Tropic of Capricorn?
(a) December 22nd
(b) March 21st
(c) June 21st
(d) September 23rd
Answer: (a) December 22nd
In simple words: The Sun's rays hit the Tropic of Capricorn directly around December 22nd. This day marks the summer solstice in the Southern Hemisphere, making it the longest day there.

🎯 Exam Tip: Memorize the dates of solstices and equinoxes and their significance regarding the Sun's position over the Tropics and Equator.

 

Question 7. When does Antarctica have the minimum temperature?
(a) In January
(b) In May
(c) In July
(d) in June
Answer: (c) In July
In simple words: Antarctica experiences its coldest temperatures in July. This is because July is winter in the Southern Hemisphere, and the region receives very little sunlight.

🎯 Exam Tip: Understand the seasonal cycles in both hemispheres. When it's winter in one, it's summer in the other, leading to opposite temperature patterns.

 

Question 8. What is the normal lapse rate?
(a) 1°C at 165 meters
(b) 2°C at 265 meters
(c) 3°C at 550 meters
(d) 4°C at 765 meters
Answer: (a) 1°C at 165 meters
In simple words: The normal lapse rate is how much the air temperature usually drops as you go higher up. On average, it gets colder by 1°C for every 165 meters you climb.

🎯 Exam Tip: The normal lapse rate is a key concept in atmospheric science. Remember the value and what it signifies for temperature changes with altitude.

 

Question 9. Gulf stream current is:
(a) warm
(b) cold
(c) polar
(d) none
Answer: (a) warm
In simple words: The Gulf Stream is a strong, warm ocean current that flows from the Gulf of Mexico across the Atlantic Ocean. It helps to make Western Europe's climate milder.

🎯 Exam Tip: Understand the impact of major ocean currents like the Gulf Stream on regional climates, distinguishing between warm and cold currents.

 

Question 10. How much of Terrestrial Radiation is released by convection?
(a) 17 units
(b) 6 units
(c) 9 units
(d) 14 units
Answer: (c) 9 units
In simple words: Out of the heat that Earth radiates back (terrestrial radiation), 9 units are released through the process of convection. Convection is how heat moves when a fluid (like air or water) flows.

🎯 Exam Tip: Recall the specific numbers from the Earth's heat budget diagrams for how heat is transferred through different processes like convection, radiation, and absorption.

 

Question 1. Match column A with column B:

Answer:
1. (d) Equator - \( 0° \) latitude line
2. (c) Tropic of Cancer - \( 23\frac {1}{2}° \) Northern latitude line
3. (b) Tropic of Capricorn - \( 23\frac {1}{2}° \) Southern latitude line
4. (e) Arctic circle - \( 66\frac {1}{2}° \) Northern latitude line
5. (a) Antarctic Circle - \( 66\frac {1}{2}° \) Southern latitude line
In simple words: These are the correct matches between Earth's important imaginary lines and their specific latitude degrees. Knowing these helps locate places on the globe.

🎯 Exam Tip: Accurately memorize the names and corresponding latitudinal values for all major imaginary lines (Equator, Tropics, Arctic/Antarctic Circles).

 

Question 2. Match column A with column B:

Answer:
(i) Lesser temperature than freezing point - (b) 27 per cent
(ii) Hot stream - (c) 14 per cent
(iii) Hot wind - (a) Loo
In simple words: This matching connects conditions with related quantities or phenomena. Loo is a hot wind. The percentages refer to parts of solar radiation, for example, 27 percent of solar radiation is reflected by clouds and 14 percent is absorbed by the atmosphere.

🎯 Exam Tip: Pay attention to keywords in both columns. For numerical relations, ensure you connect them to the correct context (e.g., specific percentages often relate to energy budget components).

RBSE Class 11 Physical Geography Chapter 12 Very Short Answer Type Questions

 

Question 1. What protects the earth from heat?
Answer: The Earth is protected from the Sun's harsh rays and intense heat by its thick atmospheric layers, which stretch for thousands of kilometers. These layers act like a shield, absorbing much of the incoming solar energy before it reaches the surface. This natural protection is vital for maintaining life.
In simple words: Earth is safe from the Sun's strong heat because of its thick atmosphere. This atmosphere stops many harmful rays.

🎯 Exam Tip: Remember that the atmosphere filters various types of radiation, not just heat, making it a crucial protective barrier.

 

Question 2. What is the sun?
Answer: The Sun is a very hot ball made of gases. It constantly gives off energy in the form of radiation. This energy is what warms our planet and fuels life, making it the primary source of all energy on Earth.
In simple words: The Sun is a giant hot gas ball. It always sends out energy that helps warm our planet.

🎯 Exam Tip: When describing celestial bodies, always include their composition (e.g., gaseous) and primary function (e.g., source of energy).

 

Question 3. What does solar radiation mean?
Answer: Solar radiation is the energy that comes out from the surface of the Sun. This energy travels through space to reach other planets, including Earth, and is crucial for Earth's climate and weather systems. It carries heat and light from the sun.
In simple words: Solar radiation is simply the energy sent out by the Sun.

🎯 Exam Tip: Distinguish solar radiation as the energy 'from' the Sun, not just the light, but the entire electromagnetic spectrum.

 

Question 4. What is the definition of insolation given by Critchfield?
Answer: Critchfield defined insolation as the radiant energy that arrives at the Earth from the Sun. It is specifically the solar radiation received by Earth's surface and atmosphere. This term highlights the incoming nature of the Sun's energy.
In simple words: Critchfield said that insolation is the Sun's energy that reaches Earth.

🎯 Exam Tip: When quoting definitions, ensure you use the exact wording provided, and remember to attribute it correctly.

 

Question 5. On the basis of temperature, earth has been divided into how many zones?
Answer: Based on temperature, the Earth has been divided into three main zones: the tropical, temperate, and frigid zones. These divisions help us understand different climates across the globe, influencing everything from vegetation to human settlement patterns.
In simple words: Earth has three temperature zones. These are hot, mild, and very cold zones.

🎯 Exam Tip: Always specify the names of the temperature zones (tropical, temperate, frigid) when asked about their number.

 

Question 7. How is the distribution of temperature represented on the map?
Answer: On a map, the way temperature is spread out (its distribution) is shown using lines called isotherms. These lines connect places that have the same temperature, making it easy to visualize temperature patterns across geographical areas.
In simple words: Isotherms are lines on a map that show how temperature is spread. They connect spots with the same temperature.

🎯 Exam Tip: Remember that "isotherms" are lines of equal temperature, just as "isobars" are lines of equal pressure.

 

Question 8. Where are rays of Sun vertical in January?
Answer: In January, the Sun's rays shine directly overhead, or vertically, on the Tropic of Capricorn. This happens in the Southern Hemisphere, making it summer there and causing the highest temperatures in that region.
In simple words: In January, the Sun's rays are straight over the Tropic of Capricorn in the Southern part of the world.

🎯 Exam Tip: Associate January with the Tropic of Capricorn and the Southern Hemisphere to remember the sun's vertical rays.

 

Question 9. Where do the rays of the sun fall vertically in the month of July?
Answer: During July, the Sun's rays fall directly vertically on the Tropic of Cancer. This occurs in the Northern Hemisphere, which experiences summer at this time, leading to warmer temperatures in that region.
In simple words: In July, the Sun's rays fall straight down on the Tropic of Cancer in the Northern part of the world.

🎯 Exam Tip: Associate July with the Tropic of Cancer and the Northern Hemisphere for the sun's vertical rays.

 

Question 10. What is the normal lapse rate of temperature?
Answer: The normal lapse rate of temperature describes how air temperature typically drops as you go higher in the troposphere. For every 165 meters you rise, the temperature usually goes down by 1°C. This is a common pattern in the lowest part of our atmosphere and explains why mountains are colder than plains.
In simple words: The normal lapse rate means that for every 165 meters you go up in the air, the temperature drops by 1°C.

🎯 Exam Tip: Remember the specific values: 1°C decrease for every 165 meters increase in altitude.

 

Question 11. What are the ideal conditions for inversion of temperature?
Answer: Ideal conditions for temperature inversion include long nights, a clear sky, calm air, dry air, and areas covered in ice (glaciated conditions). These factors allow the ground to cool very quickly, trapping colder air below warmer air, which can lead to fog and smog.
In simple words: Temperature inversion happens best with long nights, clear and dry skies, no wind, and icy places.

🎯 Exam Tip: Focus on factors that promote rapid surface cooling and prevent air mixing when identifying ideal inversion conditions.

 

Question 12. Why is the temperature of Shimla found to be less than that of Delhi?
Answer: Shimla's temperature is lower than Delhi's because Shimla is located at a much higher altitude. As altitude increases, the air becomes thinner and holds less heat, leading to cooler temperatures. This natural phenomenon is why hill stations are usually colder than cities in the plains, even when they are at similar latitudes.
In simple words: Shimla is colder than Delhi because it is much higher up. Higher places have thinner air which is naturally cooler.

🎯 Exam Tip: Always relate temperature differences between places like Shimla and Delhi to their altitude and the normal lapse rate of temperature.

 

Question 14. How do the clouds control - temperature?
Answer: Clouds play a role in controlling temperature by reflecting sunlight back into space. In areas with clouds and rain, the temperature often stays cooler because the clouds prevent much of the sun's energy from reaching the ground. In cloud-free areas, more solar energy reaches the surface, leading to higher temperatures, showcasing their moderating effect.
In simple words: Clouds keep places cooler by bouncing sunlight away. Where there are no clouds, the sun heats the ground more, making it hotter.

🎯 Exam Tip: Highlight both the reflective (cooling) and insulating (warming at night) properties of clouds when discussing their effect on temperature.

 

Question 15. What is meant by heat budget?
Answer: The Earth's heat budget refers to the overall balance between the heat energy the Earth and its atmosphere receive from the Sun and the heat energy they lose back into space. This balance ensures a stable global temperature, preventing the planet from continually warming or cooling.
In simple words: Heat budget is about how much heat Earth gets from the Sun and how much heat it sends back. It's a balance of heat in and heat out.

🎯 Exam Tip: Define heat budget as the "balance" of incoming and outgoing radiation to score full marks.

 

Question 16. Why does the sun's entire heat not reach the ground?
Answer: The Sun's entire heat does not reach the ground because various atmospheric processes occur between the Sun and the Earth. These processes include the absorption, reflection, and scattering of solar rays by gases, clouds, and dust particles in the atmosphere. Because of this, only a portion of the total solar energy reaches Earth's surface, while the rest is dissipated.
In simple words: Not all of the Sun's heat gets to the ground. This is because the atmosphere absorbs, reflects, and scatters some of the sun's rays before they can reach Earth's surface.

🎯 Exam Tip: List the three main atmospheric processes (absorption, reflection, scattering) that reduce solar radiation reaching the surface.

RBSE Class 11 Physical Geography Chapter 12 Short Answer Type Questions (SA-1)

 

Question 1. Explain the utility of the atmosphere.
Answer: The atmosphere is extremely important for Earth's survival, offering several key benefits:
1. It acts as a thick shield, protecting our planet from the sun's intense heat and harmful radiation.
2. At night, the atmosphere works like a warm blanket, keeping us from getting too cold by trapping heat.
3. The gases in the atmosphere, like oxygen, are vital for humans and other living things to breathe.
4. It also blocks dangerous ultraviolet rays from the sun, which helps protect life on Earth from skin damage and other harm.
The atmosphere thus regulates Earth's temperature and supports all forms of life.
In simple words: The atmosphere is very important. It shields Earth from hot sun rays and blocks bad ultraviolet rays. It also keeps us warm at night, like a blanket. The gases in it, such as oxygen, help us live.

🎯 Exam Tip: When explaining the utility of the atmosphere, focus on its protective, regulatory, and life-sustaining functions.

 

Question 3. Explain the isotherms of the Southern Hemisphere in January.
Answer: In January, the Sun's rays hit the Tropic of Capricorn directly in the Southern Hemisphere, causing summer there. Because of this, the temperature lines (isotherms) in this hemisphere generally run parallel to the lines of latitude. Towards the very south, around Antarctica, the \( 0°C \) isotherm completely encircles the continent from all directions, indicating extreme cold. Further north, the \( 10°C \) and \( 20°C \) isotherms can be seen crossing South America, parts of Australia, and then curving upwards after entering the ocean near Southwest Africa. The \( 40°C \) isotherm generally follows the \( 60° \) South latitude line. This pattern shows how temperatures change greatly with distance from the equator and the moderating influence of oceans.
In simple words: In January, the sun shines directly on the southern half of the Earth, making it summer there. Temperature lines mostly follow latitude lines. Around Antarctica, the freezing line (\( 0°C \)) circles it. Other warmer lines (\( 10°C, 20°C \)) cross over South America, Australia, and Africa, heading towards the ocean. The \( 40°C \) line stays around the \( 60° \) South latitude.

🎯 Exam Tip: When describing isotherms, mention their general direction (parallel to latitudes or skewed) and their typical values in specific regions during the given month.

 

Question 4. How does uneven distribution of temperature on earth affect the climate and weather?
Answer: The uneven way temperature is spread across Earth greatly affects its climate and weather patterns. In tropical areas, the sun's rays are direct all year, leading to consistently high temperatures and a hot, tropical climate. In temperate zones, temperatures are lower, and there are more distinct seasonal changes, resulting in a temperate climate. Lastly, in very high latitudes, temperatures are very low, and snow covers the ground for most of the year, creating a polar climate. Clearly, how temperature varies on the surface has a huge impact on the world's climates and creates distinct ecosystems in each region.
In simple words: The Earth's temperature is not the same everywhere, which changes climates. Hot zones have sun all year. Mild zones have changing seasons and cooler weather. Cold zones have snow most of the year. So, different temperatures create different types of weather and climates.

🎯 Exam Tip: Connect the three main climatic zones (tropical, temperate, polar) directly to the intensity and angle of incoming solar radiation to explain temperature distribution.

 

Question 6. The annual temperature range is highest in the plains of Siberia. Why?
Answer: The annual temperature range is highest in Siberia, located in northern Eurasia, because it experiences a continental climate. Oceanic currents like the Gulf Stream, which warm coastal areas, have very little impact deep within the continent. This means inland Siberia gets extremely cold in winter, often falling below \( 0°C \), and can be quite warm in summer due to its large landmass heating up quickly. The combination of its vast landmass, high latitude, and distance from moderating ocean influences results in the world's largest temperature difference between seasons, a phenomenon known as continentality.
In simple words: Siberia has the biggest temperature changes each year because it's far from the ocean. Oceans usually keep temperatures mild. Since Siberia is inland, it gets very cold in winter and warm in summer, causing a huge difference in temperature.

🎯 Exam Tip: The key term here is "continentality" – the effect of being far from oceans, which leads to extreme temperature ranges.

 

Question 7. Explain the difference between insolation and terrestrial radiation.
Answer: Insolation and terrestrial radiation are two different ways heat moves to and from Earth.
* **Insolation:** This is the solar energy that reaches Earth's surface and atmosphere from the Sun. It travels as short waves at a speed of about 186,000 miles per second. This incoming energy powers most of Earth's atmospheric processes and keeps the planet warm.
* **Terrestrial Radiation:** After Earth absorbs insolation and heats up, it then releases this heat back into space. This process is called terrestrial radiation. It's the long-wave radiation given off by the Earth's surface, similar to how any warm object radiates heat. This outgoing radiation helps balance the Earth's heat budget.
In simple words: Insolation is the heat Earth gets from the Sun. Terrestrial radiation is the heat Earth sends back out after warming up. The Sun sends short waves, and Earth sends long waves.

🎯 Exam Tip: Clearly differentiate between the source (Sun vs. Earth), type of waves (short vs. long), and direction of heat transfer (incoming vs. outgoing).

 

Question 1. Explain the importance of insolation.
Answer: Insolation, which is the Sun's heat reaching Earth, is incredibly important for many reasons:
1. Without insolation, Earth would be a frozen planet, completely covered in snow and ice, unable to support liquid water.
2. Receiving insolation forms the foundation for all life on Earth; without it, our planet would be empty and lifeless, as photosynthesis would be impossible.
3. The diverse types of plants and vegetation we see today could only grow because of the Sun's energy, which drives their growth and development.
4. Insolation also prevents Earth from being a dark planet, providing the light necessary for vision and many biological processes.
5. It helps create all the natural features, seasons, climates, humidity, and rainfall patterns we experience. These wouldn't exist without it, leading to a static environment.
6. Humans, animals, and birds all rely on the Sun's heat for their daily activities and survival, regulating their body temperatures and behaviors.
7. Finally, from insolation, the atmosphere receives heat due to which heat budget is retained, ensuring that Earth maintains a habitable temperature range.
In simple words: Insolation (Sun's heat) is vital. It keeps Earth from freezing, makes life possible, helps plants grow, and lights up our planet. It also creates seasons and weather. All living things use Sun's heat, and it balances Earth's temperature.

🎯 Exam Tip: Structure your answer using clear points covering life, climate, light, and planetary balance to show a comprehensive understanding.

 

Question 2. Describe the temperature zones found on the globe on latitudinal basis.
Answer: The Earth's surface doesn't have the same temperature everywhere. Temperature distribution is mostly decided by latitude, as it affects how directly the sun's rays hit the surface. Based on latitude, the Earth is divided into three main temperature zones:
1. **The Tropical Zone:** This zone is located around the equator, stretching between \( 23\frac {1}{2}° \) North and \( 23\frac {1}{2}° \) South latitudes. It receives direct sunlight throughout the year, so its average temperature is warm, usually between \( 24-26°C \). This consistent warmth supports lush biodiversity.
2. **The Temperate Zone:** Found between \( 23\frac {1}{2}° \) and \( 66\frac {1}{2}° \) North and South latitudes in both hemispheres. This zone has moderate temperatures, generally below \( 24°C \), with distinct seasons. The temperature decreases as you move closer to the poles, leading to varied landscapes.
3. **The Frigid Zone:** These are the coldest regions, located from \( 66\frac {1}{2}° \) North and South latitudes up to the poles. They receive very little direct sunlight and experience extremely low temperatures, often below freezing for most of the year, leading to permanent ice and snow. This extreme cold limits vegetation to hardy species.
In simple words: Earth has different temperature zones based on how far they are from the equator. The **Tropical Zone** around the middle is very hot all year. The **Temperate Zone** is a bit further from the middle; it has milder temperatures and four seasons. The **Frigid Zone** is near the poles, and it is very cold and icy all the time.

🎯 Exam Tip: Clearly state the latitudinal boundaries for each zone and describe their characteristic temperature patterns and seasonality.

 

Question 3. What is the distribution of the isotherms in July?
Answer: In July, the Sun's position makes the Northern Hemisphere warmer, with direct sunlight falling on the Tropic of Cancer. This results in the highest temperatures in continental interiors and tropical deserts, while the equator stays around \( 27°C \). In the Northern Hemisphere, isotherms (lines of equal temperature) bend a lot over landmasses, reflecting how land heats up more than water. But in the Southern Hemisphere, they tend to run parallel to the lines of latitude because of the vast oceans moderating temperatures. For instance, areas like northern Siberia, Europe, and Alaska show \( 10°C \) isotherms. Central Asia, northern Japan, southwestern Europe, and Canada generally have \( 20°C \) isotherms. Hotter regions like South Asia, northern Africa, and Mexico feature \( 30°C \) isotherms. In contrast, the Southern Hemisphere's central Australia and parts of South America show \( 20°C \) isotherms, extending to \( 10°C \) in southern Australia and America. This pattern shows how land and water affect temperature distribution differently, especially in summer.
In simple words: In July, the Northern half of Earth gets warmer as the sun shines directly on the Tropic of Cancer. Land areas get very hot, while the equator is around \( 27°C \). In the Northern half, temperature lines bend a lot over land. In the Southern half, they usually stay straight. Places like Siberia, Europe, and Alaska have \( 10°C \) lines. Japan, Canada, and parts of Europe have \( 20°C \) lines. Very hot places like North Africa and South Asia have \( 30°C \) lines. In the Southern half, Australia and South America have \( 20°C \) and \( 10°C \) lines.

🎯 Exam Tip: Describe how isotherms behave differently over land (skewed) and water (parallel to latitudes) in July, linking it to the summer season in the Northern Hemisphere.

 

Question 4. Explain the inversion of temperature.
Answer: Normally, in the troposphere, the air temperature gets cooler as you go higher. However, in certain specific situations, this changes, and the air temperature actually increases with altitude instead of decreasing. This unusual event is known as temperature inversion or simply inversion. This phenomenon is critical as it can trap pollutants close to the ground, affecting air quality.
**Conditions Responsible for Temperature Inversion:**
1. **Dry Air:** When the air is dry, it cannot absorb and hold heat well. This allows the Earth's surface to cool down quickly after radiating heat, leading to colder air near the ground.
2. **Glaciated Conditions:** In polar or icy regions, continuous outward radiation of cold energy from the ice leads to rapid temperature inversions due to the surface losing heat efficiently.
3. **Stable Weather:** During stable weather, without much air movement, heat radiation from the Earth's surface can continue uninterrupted for long periods. This allows significant temperature differences to build up at various heights.
4. **Long, Cold Nights:** Longer winter nights provide more time for the ground to radiate heat away. This makes the surface very cold and traps this cold, dense air beneath warmer layers higher up.
5. **Clear Sky:** A clear sky at night allows the Earth's heat to escape directly into space without clouds reflecting it back. This causes the ground to cool rapidly, increasing the likelihood of an inversion.
6. **Calm Air:** Without strong winds, the cold air that forms near the surface is not mixed with warmer air above. This allows the temperature inversion to strengthen and persist, often leading to fog or smog.
In simple words: Usually, air gets colder as you go up. But sometimes, air gets warmer as you go up; this is called temperature inversion. It happens best on long, clear, calm, and dry nights, especially in icy places, because the ground cools faster. This can trap cold air near the ground.

🎯 Exam Tip: To explain temperature inversion fully, remember to define it first, then list the key conditions that cause it, such as long nights, clear skies, and calm air.

 

Question 5. Explain the economic impact of inversion of temperature.
Answer: Temperature inversion has several economic impacts on the surface:
1. It often leads to thick fog, which can disrupt travel and transport, especially for aircraft and ships, causing delays and financial losses.
2. In valley areas, the warmer air trapped higher up can create ideal conditions for human settlements, as the cold, dense air settles in the lower parts, pushing settlements to warmer slopes.
3. During winter, smoke and moisture in cities combine with inversion to create dense smog, causing health problems, reducing visibility, and impacting daily activities and tourism.
4. The extremely cold air trapped in the lower parts of valleys can freeze and destroy crops, leading to agricultural losses for farmers.
5. Conversely, the upper parts of hill valleys, being warmer due to the inversion, become excellent for growing fruits, nuts, and for plantation agriculture, offering unique farming opportunities.
In simple words: Temperature inversion affects our economy. It causes heavy fog, which makes travel hard. Valleys become good for living in higher parts. City smoke and moisture create bad fog in winter. Crops in lower valleys can freeze and die. But higher parts of valleys are good for growing fruits and nuts.

🎯 Exam Tip: Provide specific examples for each economic impact, covering both negative (fog, crop damage) and positive (settlement, specific agriculture) effects.

 

Question 6. Explain the heat budget of the earth and the atmosphere in brief.
Answer: The Earth's heat budget describes how the Earth and its atmosphere maintain a balance between the incoming solar energy and the outgoing heat. This balance is crucial for keeping global temperatures stable.
Let's assume the initial solar radiation is 100 units:
**(A) Initial Solar Radiation (100 units):**
* **Reflected and Scattered (35 units):**
(i) Reflected by the clouds: 27%
(ii) Reflected from the surface: 2%
(iii) Scattered into space by the atmosphere: 6%
**(B) Earth's Heating Budget (51 units received by Earth):**
* The remaining solar radiation is 65 units (\( 100 - 35 \)). Out of this:
* 14 units are absorbed by the atmosphere (water vapor, dust particles).
* 51 units are actually received by the Earth's surface (34 units directly, 17 units through atmospheric light).
**(C) Atmosphere's Heat Budget (48 units absorbed and re-radiated):**
* The atmosphere directly absorbs 14 units of terrestrial radiation.
* It receives 34 units from outgoing terrestrial radiation.
In total, Earth and atmosphere system radiates back all 100 units to space, maintaining a thermal equilibrium. If the Earth keeps more heat than it sends out, the planet will warm up, leading to climate change.
In simple words: Earth's heat budget is how the planet keeps its temperature steady by balancing heat from the Sun with heat it sends back out. Out of 100 units of Sun's energy, 35 units are reflected away by clouds and Earth's surface, or scattered by air. Earth gets 51 units directly or indirectly. The atmosphere also takes in 14 units from the Sun's heat and 34 units from Earth's heat, sending it all back to space. This keeps Earth from getting too hot or too cold.

🎯 Exam Tip: Quantify the heat budget components (e.g., 35% reflected, 51% absorbed by Earth) to demonstrate a precise understanding of the energy flow.