All questions of Climatology for UPSC CSE Exam

All statements are correct; hence answer is (d). There are six major controls of the climate of any place. They are latitude, altitude, pressure and wind system, distance from the sea (continentality), ocean currents and relief features.

Nitrogen as a Major Constituent of the Atmosphere

Nitrogen is one of the major constituents of the Earth's atmosphere, comprising about 79% of the atmospheric gases. It plays a crucial role in various biological processes and is an essential element for the survival and growth of living organisms.

1. Nitrogen as an Essential Constituent of Organic Compounds

Nitrogen is an essential component of organic compounds such as amino acids and proteins. Amino acids are the building blocks of proteins, which are vital for the structure and functioning of cells, tissues, and organs in all living organisms. Proteins have various functions in the body, including enzyme catalysis, cell signaling, transportation of molecules, and structural support.

The presence of nitrogen in organic compounds allows for the formation of peptide bonds between amino acids, leading to the synthesis of proteins. Without nitrogen, the synthesis of these essential biomolecules would not be possible, and life as we know it would not exist.

2. Nitrogen as a Principal Source of Free Nitrogen

The principal source of free nitrogen in the environment is the action of soil microorganisms and associated plant roots on atmospheric nitrogen. Nitrogen gas (N2) is abundant in the atmosphere, but most organisms cannot directly use it in this form. They require nitrogen in a more accessible form, such as ammonia (NH3) or nitrate (NO3-).

Certain nitrogen-fixing bacteria present in the soil, such as Rhizobium and Azotobacter, have the ability to convert atmospheric nitrogen into a usable form. These bacteria form symbiotic relationships with certain plants, such as legumes, where they colonize the roots and convert nitrogen gas into ammonia through a process called nitrogen fixation.

The ammonia produced by nitrogen-fixing bacteria can be further converted into nitrate by other soil bacteria in a process called nitrification. This nitrate can then be taken up by plants through their roots and utilized in the synthesis of organic compounds, such as amino acids and proteins. Thus, the action of soil microorganisms and associated plant roots is crucial in making atmospheric nitrogen available to living organisms.

Conclusion

Both statements provided in the question are correct. Nitrogen is indeed an essential constituent of organic compounds such as amino acids and proteins. Additionally, the principal source of free nitrogen is the action of soil microorganisms and associated plant roots on atmospheric nitrogen. Understanding the role of nitrogen in biological processes and its availability in the environment is important for studying various ecological and agricultural systems.

The concept of albedo refers to the ability of a surface to reflect sunlight back into space. The higher the albedo of a surface, the more sunlight it reflects, resulting in less absorption and less warming of the atmosphere. Conversely, a lower albedo means that a surface absorbs more sunlight, leading to more warming.

Lowest albedo: Moist ploughed soil

Moist ploughed soil is likely to have the lowest albedo among the given options. This is because soil is generally dark in color, which means that it absorbs more sunlight. Additionally, moist soil tends to be more reflective than dry soil, but still absorbs more sunlight than other materials like snow and clouds.

Other options and their albedo

- Thick cloud: Clouds have a high albedo, as they reflect a significant amount of sunlight back into space. Therefore, thick cloud is unlikely to have the lowest albedo.
- Fresh snow in Antarctica: Snow has a high albedo, as it reflects sunlight very effectively. Therefore, fresh snow in Antarctica is also unlikely to have the lowest albedo.
- Mirror: Mirrors have a very high albedo, as they reflect almost all of the sunlight that falls on them. Therefore, a mirror is also unlikely to have the lowest albedo.

Conclusion

In conclusion, moist ploughed soil is likely to have the lowest albedo among the given options. This means that it absorbs more sunlight, leading to more warming of the atmosphere. It is important to understand the concept of albedo in order to better understand the impact of different surfaces and materials on the Earth's climate.

Temperature inversion is most common in Mountain valleys.

Explanation:

Temperature inversion refers to a reversal of the normal atmospheric temperature gradient, where the temperature increases with altitude. In other words, instead of the temperature decreasing as we go higher in the atmosphere, it actually increases. This phenomenon is caused by the trapping of cool air near the surface of the Earth by a layer of warm air above it.

Inversions can occur in various locations, but they are most common in mountain valleys. Here's why:

1. Geographic Features:
- Mountain valleys are characterized by their topography, with high mountains surrounding a narrow valley floor.
- This topography plays a crucial role in the formation of temperature inversions.
- During the day, the sun heats up the valley floor, causing the air near the surface to warm and rise.
- However, at night, the valley floor cools rapidly due to radiative cooling, causing the air near the surface to become colder than the air above it.

2. Cold Air Drainage:
- In mountain valleys, cold air tends to drain down the slopes and accumulate in the valley bottom.
- This cold air becomes trapped beneath a layer of warmer air, leading to the formation of a temperature inversion.
- The surrounding mountains act as barriers, preventing the cold air from mixing with the warmer air above.

3. Stable Atmospheric Conditions:
- Temperature inversions are more likely to occur when the atmosphere is stable.
- In stable atmospheric conditions, there is little vertical mixing of air masses, allowing the inversion layer to persist.
- Mountain valleys often experience stable atmospheric conditions, especially during calm and clear nights when radiative cooling is most effective.

4. Local Climate:
- Mountain valleys tend to have specific climatic conditions that favor the formation of temperature inversions.
- The cool air trapped in the valley can lead to the accumulation of pollutants, such as smoke or fog, which further enhance the inversion layer.
- This can result in poor air quality and reduced visibility in these areas.

In conclusion, temperature inversions are most common in mountain valleys due to the geographic features, cold air drainage, stable atmospheric conditions, and local climate characteristics associated with these regions.

Explanation:

1. These are low-pressure regions:
Anticyclones are actually high-pressure systems, not low-pressure systems. In an anticyclone, the air is sinking and spreading outwards from a central region, creating higher pressure at the surface. This high-pressure system is characterized by clear skies, light winds, and dry weather conditions. So, statement 1 is incorrect.

2. Their extent is always small:
Anticyclones are typically smaller in size compared to other weather systems such as cyclones. They usually span a few hundred kilometers in diameter. Due to their smaller size, they have a more localized impact on weather patterns. So, statement 2 is correct.

3. Cloudy and precipitation conditions exist along with the cyclone:
This statement is incorrect. Anticyclones are associated with clear skies and dry weather conditions. The sinking air in an anticyclone inhibits the formation of clouds and precipitation. Instead, they are characterized by stable atmospheric conditions, which result in fair weather with minimal cloud cover and low chances of rainfall.

Conclusion:
Based on the explanations above, statement 1 is incorrect, statement 2 is correct, and statement 3 is incorrect. Therefore, the correct answer is option 'C' - only statement 2 is true.

Rotation of earth on its axis gives rise to Coriolis force.

Inter-tropical Convergence Zone (ITCZ)

The Inter-tropical Convergence Zone (ITCZ) is a significant belt of low pressure around the Earth's equator where the northeast and southeast trade winds converge. It is characterized by rising air, unstable weather conditions, and abundant rainfall. Let's evaluate each statement:

Statement 1: It is an area near the Equator where northeast and southeast trade winds meet.
This statement is correct. The ITCZ is formed by the convergence of the northeast trade winds from the Northern Hemisphere and the southeast trade winds from the Southern Hemisphere. As these trade winds converge, they ascend due to the low-pressure system, resulting in the formation of clouds and precipitation.

Statement 2: The zone is referred to as the doldrums because of its erratic weather patterns with stagnant calms and violent thunderstorms.
This statement is also correct. The region of the ITCZ is often referred to as the doldrums because of its unpredictable and erratic weather patterns. The convergence of trade winds creates areas of calm or light and variable winds, which can lead to stagnation and little to no wind movement. Additionally, thunderstorms are common in this area due to the convective activity caused by the rising warm air.

Statement 3: If ITCZ is north of the equator, the southeast trade wind changes to a southwest wind as it crosses the equator because of the Coriolis effect.
This statement is correct as well. The Coriolis effect, caused by the Earth's rotation, influences the wind direction. As the southeast trade winds approach the ITCZ from the Southern Hemisphere, they are deflected to the left (westward) in the Northern Hemisphere due to the Coriolis effect. Therefore, as they cross the equator, the southeast trade winds change direction and become southwest winds.

In conclusion, all three statements are correct. The ITCZ is an area near the equator where northeast and southeast trade winds converge. It is referred to as the doldrums due to its erratic weather patterns with stagnant calms and violent thunderstorms. The Coriolis effect causes the southeast trade winds to change direction to southwest winds as they cross the equator.

Coriolis force is absent at the equator. Due to this, winds blowing from high-pressure sub-tropics to low-pressure tropics do not form a circulatory pattern around a low-pressure zone.

Assertion and Reasoning

Assertion: The annual range of temperature is greater in the Northern Hemisphere than that in the Southern Hemisphere.

Reasoning: Northern Hemisphere has more land area than Southern Hemisphere.

Explanation

The correct option is A, i.e., A is correct, and R is an appropriate explanation of A.

The annual range of temperature refers to the difference between the maximum and minimum temperatures recorded in a year. The Northern Hemisphere has more land area than the Southern Hemisphere. Land areas heat up and cool down faster than water bodies. As a result, the temperature changes are more drastic and the annual range of temperature is greater in the Northern Hemisphere.

For instance, in the Northern Hemisphere, the annual range of temperature in some regions can be as much as 50-60°C. In contrast, the annual range of temperature in the Southern Hemisphere is comparatively lower, with some regions having an annual range of 20-30°C.

Conclusion

Thus, the assertion is correct, and the reasoning is an appropriate explanation of the assertion. The difference in land area between the Northern Hemisphere and Southern Hemisphere is responsible for the difference in the annual range of temperature.

Zero Coriolis force at the equator:
- The Coriolis force is responsible for the deflection of winds in the Northern and Southern Hemispheres.
- At the equator, the Coriolis force is nearly zero due to the minimal effect of the Earth's rotation on the winds.

Presence of roaring forties:
- The roaring forties are strong westerly winds found in the Southern Hemisphere, generally between 40 and 50 degrees latitude.
- These winds are located much farther from the equator and do not directly impact the deflection of winds at the equator.

A large number of land breaks and bays:
- Landmasses and bodies of water, such as bays, can influence the direction and speed of winds.
- At the equator, there are a large number of land breaks and bays that can disrupt the flow of winds, leading to less deflection.

In conclusion, the winds are not deflected with great force at the equator primarily due to the zero Coriolis force at the equator. The presence of the roaring forties and a large number of land breaks and bays also play a role, but they are not as significant as the absence of the Coriolis force at the equator.

Explanation:

Absolute Humidity:
Absolute humidity refers to the actual amount of moisture present in the air, regardless of temperature. It is a measure of the total water vapor content in a given volume of air and is usually expressed in grams per cubic meter (g/m3) or grams per kilogram (g/kg).

Relative Humidity:
Relative humidity is the ratio of the actual amount of moisture present in the air to the maximum amount of moisture the air can hold at a particular temperature. It is expressed as a percentage and provides a measure of how close the air is to saturation. Relative humidity is dependent on both the temperature and the absolute humidity.

Specific Humidity:
Specific humidity is a measure of the actual amount of moisture present in the air on a mass basis. It is the ratio of the mass of water vapor to the total mass of the air parcel. Specific humidity is expressed in grams per kilogram (g/kg) and is not dependent on temperature.

Analysis of the Statements:
1. Absolute humidity is the water content of the air.
This statement is correct. Absolute humidity refers to the actual amount of moisture present in the air.

2. Relative humidity, expressed as a per cent, measures the current absolute humidity relative to the maximum for that temperature.
This statement is correct. Relative humidity is a measure of the current absolute humidity relative to the maximum amount of moisture the air can hold at a particular temperature.

3. Specific humidity is a ratio of the water vapor content of the mixture to the total air content on a mass basis.
This statement is incorrect. Specific humidity is a ratio of the water vapor content of the mixture to the total mass of the air parcel, not the total air content. It is not dependent on temperature.

Conclusion:
Based on the analysis, statement 3 is incorrect, while statements 1 and 2 are correct. Therefore, the correct answer is option 'D' - None of the above.

The general distribution of winds throughout the lower atmosphere is known as planetary winds. Confined within some latitudinal belts, these winds blow rather regularly throughout the year and are basically controlled by the latitudinal pressure belts.

The main planetary winds are (i) the North-east and the South-east Trade winds, (ii) the Temperate Westerlies and (iii) the Polar Easterlies, which blow from the polar high-pressure area to the temperate low-. Pressure area.

All of them are affected by Coriolis force (Earth's rotation on its axis), and migration of pressure belts apart from how heat patterns vary across the Earth (creating pressure difference).

Explanation:
The thermal equator is an imaginary circle around the Earth that connects the points where the highest mean annual temperature is recorded at each longitude. The following points explain why the thermal equator is slightly north of the geographical equator:

- Solar insolation is comparatively much higher in the Northern Hemisphere than in the Southern Hemisphere. This is due to the fact that the Earth's orbit is not circular but slightly elliptical. As a result, the Earth is closer to the Sun during the Northern Hemisphere summer than during the Southern Hemisphere summer. This means that there is more solar radiation falling on the Northern Hemisphere, leading to higher temperatures.

- The Northern Hemisphere is dominated by land, which heats up faster than water. Land has a lower heat capacity than water, which means that it takes less energy to raise its temperature. This is why temperatures in the interior of continents can be much higher than temperatures on the coasts. In contrast, the Southern Hemisphere is dominated by ocean waters, which have a higher heat capacity and take longer to warm up. This leads to lower temperatures in the Southern Hemisphere.

Therefore, both factors contribute to the fact that the thermal equator is slightly north of the geographical equator. Option B is the correct answer.

In January, Earth is closer to Sun (perihelion) while in July, it experiences aphelion. But due to uneven distribution of land and sea in both hemispheres and air circulation, differences are evened out.

Explanation:

1. Climate change is leading to increased frequency and intensity of heatwaves.
Climate change refers to long-term changes in temperature, precipitation, wind patterns, and other aspects of the Earth's climate system. It is widely accepted that human activities, particularly the burning of fossil fuels, have significantly contributed to climate change. As a result, the Earth's average temperature is increasing, leading to various impacts, including an increase in the frequency and intensity of heatwaves. Heatwaves are prolonged periods of excessively hot weather, typically lasting for several days or even weeks. The rising temperatures due to climate change create favorable conditions for heatwaves to occur more frequently and with greater intensity.

2. In India, it is most commonly experienced in North-Western regions.
India experiences heatwaves across various regions, but they are most commonly observed in the North-Western parts of the country. This region includes states like Rajasthan, Gujarat, Punjab, Haryana, and parts of Madhya Pradesh. These areas are known for their arid or semi-arid climate, which makes them more prone to extreme heat conditions. Factors such as geographical location, proximity to deserts, and the absence of significant water bodies contribute to the higher occurrence of heatwaves in these regions.

3. As per NDMA guidelines, when local temperature is constantly above 40°C, heatwaves must be declared by local authorities.
The National Disaster Management Authority (NDMA) is responsible for planning, coordinating, and implementing measures for disaster management in India. The NDMA has issued guidelines regarding the declaration of heatwaves by local authorities. According to these guidelines, a heatwave is declared when the local temperature consistently remains above 40°C for a certain period. This threshold temperature helps authorities in identifying and responding to heatwave situations, ensuring appropriate measures are taken to protect vulnerable populations from the adverse effects of extreme heat.

Correct Answer:
Based on the given information, the correct answer is option 'A' - 1 and 2 only. The statement that climate change is leading to increased frequency and intensity of heatwaves is supported by scientific consensus. The statement about heatwaves being most commonly experienced in North-Western regions of India is also accurate. However, there is no mention of the NDMA guidelines in the given information, so the statement regarding the declaration of heatwaves by local authorities is not supported.

Gravitational forces acting on air

- The reason why air closer to the Earth's surface is heavier is due to the gravitational forces acting on it.
- Gravity is a force that pulls objects towards the center of the Earth. It is responsible for keeping the atmosphere in place.
- The force of gravity is stronger closer to the Earth's surface and weaker as you move further away from it.
- As a result, the air molecules near the surface experience a greater gravitational force compared to those in the upper atmosphere.

Effect of gravitational forces on air

- The gravitational force causes the air molecules to be pulled towards the Earth's surface, creating pressure.
- This pressure is known as atmospheric pressure and it decreases with increasing altitude.
- The weight of the air above a certain point in the atmosphere creates pressure at that point.
- Therefore, the air closer to the Earth's surface experiences a higher atmospheric pressure compared to the air in the upper atmosphere.

Density and weight of air

- The air near the Earth's surface is denser compared to the air in the upper atmosphere.
- Density is the mass of an object per unit volume. The denser the air, the more mass it contains in a given volume.
- The weight of an object is the force exerted on it due to gravity. The weight of air is determined by its mass.
- Since the air near the Earth's surface has a higher density, it also has a higher mass per unit volume, resulting in a higher weight.

Conclusion

- In conclusion, the air closer to the Earth's surface is heavier because of the gravitational forces acting on it.
- These forces cause the air molecules to be pulled towards the Earth, creating higher atmospheric pressure and denser air near the surface.
- Understanding the effects of gravity on the atmosphere is important for studying weather patterns, air circulation, and other atmospheric phenomena.

Assertion (A): The eastern coasts of continents within the tropics have much heavier rainfall than the interiors of the west coasts.
Reason (R): All western coasts fall in the rain shadow zone.

The correct answer is option 'C', which states that Assertion (A) is correct, but Reason (R) is incorrect.

Explanation:

Eastern Coasts of Continents within the Tropics have Heavier Rainfall:
- The eastern coasts of continents within the tropics, such as the eastern coast of India or the eastern coast of Africa, receive heavier rainfall compared to the interiors of the west coasts.
- This is due to the prevailing wind patterns in the tropics, specifically the trade winds.
- The trade winds blow from east to west in the tropics, carrying moist air from the oceans towards the western coasts of continents.
- As the moist air encounters the landmass, it is forced to rise, leading to the formation of clouds and subsequent rainfall along the western coasts.
- This phenomenon is known as orographic rainfall, where the moist air is lifted over a mountain or elevated terrain, resulting in enhanced precipitation.
- As a result, the western coasts of continents within the tropics receive significant rainfall.

Rain Shadow Zone:
- The rain shadow zone refers to the area that lies on the leeward side of a mountain range or elevated terrain.
- When moist air is lifted over a mountain range, it cools and condenses, leading to rainfall on the windward side of the mountain.
- However, as the air descends on the leeward side, it warms and dries up, resulting in reduced rainfall and arid conditions.
- This creates a rain shadow zone, which is characterized by low precipitation and dry climate.
- The rain shadow effect is prominent on the leeward side of mountain ranges, where the prevailing winds are blocked by the mountains, preventing the moist air from reaching the area.

Reason (R) is Incorrect:
- While it is true that western coasts often experience the rain shadow effect, it is not true that all western coasts fall in the rain shadow zone.
- There are several factors that determine the occurrence of the rain shadow effect, including the direction of prevailing winds, the height and orientation of the mountain range, and the distance from the coast.
- In some cases, the western coasts may not be affected by the rain shadow effect and may receive significant rainfall due to other atmospheric factors or geographical features.

Conclusion:
- The assertion that the eastern coasts of continents within the tropics have heavier rainfall than the interiors of the west coasts is correct.
- However, the reason that all western coasts fall in the rain shadow zone is incorrect, as it does not consider the various factors that determine the occurrence of the rain shadow effect.

Why do rain clouds appear black in colour despite having the Sun above them?

Explanation:
Rain clouds appear black in colour despite having the Sun above them primarily because clouds scatter the light they receive. Let's understand each option given in the question to arrive at the correct answer:

1. Clouds accumulate electrostatic charge:
This option is incorrect as the accumulation of electrostatic charge in clouds does not cause them to appear black in colour.

2. Rain-bearing clouds absorb most of the solar insolation falling on them:
This option is incorrect as rain-bearing clouds do not absorb most of the solar insolation falling on them. Instead, they reflect and scatter a significant portion of the sunlight they receive.

3. Clouds scatter light received by them:
This option is correct. Clouds are made up of tiny water droplets or ice crystals, which act as scattering centers for the incoming sunlight. When sunlight passes through a cloud, the individual water droplets scatter the light in all directions. This scattering of light causes the cloud to appear white or gray to the observer on the ground. However, when rain clouds become thicker and denser, they scatter more light and absorb less, resulting in a darker appearance. The thicker the cloud, the more light it scatters, making it appear darker or even black.

Therefore, the correct answer is option 'D' - 3 only, which states that rain clouds appear black in colour because clouds scatter the light received by them.

In conclusion, rain clouds appear black in colour despite having the Sun above them because of the scattering of light by the water droplets or ice crystals present in the clouds. The thicker and denser the clouds, the more light they scatter, resulting in a darker appearance.

Explanation:
Rainfall patterns are influenced by various factors, including solar insolation, atmospheric circulation, and temperature gradients. When moving from the equator to the poles, there is a general trend of reducing rainfall. This can be explained by the change in solar insolation.

Change in solar insolation:
Solar insolation refers to the amount of solar radiation or sunlight received at a particular location. The intensity of solar radiation decreases as one moves away from the equator towards the poles. This is mainly due to the curvature of the Earth and the angle at which sunlight reaches the surface.

- At the equator, the Sun's rays are more direct, resulting in higher solar insolation. This leads to warmer temperatures and increased evaporation, which in turn contributes to higher rainfall.
- As one moves towards the poles, the angle at which sunlight reaches the surface becomes more oblique. This reduces the amount of solar radiation received, resulting in lower temperatures and decreased evaporation. Consequently, the amount of moisture available for condensation and rainfall decreases.

Other factors:
While solar insolation is the primary factor influencing rainfall patterns from the equator to the poles, other factors can also play a role:

- Atmospheric circulation: The movement of air masses and prevailing winds can affect rainfall patterns. However, in the context of the given options, it is not the main factor responsible for the reducing rainfall pattern.
- Formation of wavy isotherms at the equator: Isotherms are lines on a map connecting points with equal temperature. The formation of wavy isotherms at the equator can result in localized convective rainfall, but it does not explain the general trend of reducing rainfall when moving polewards.
- Movement of the jet stream along the way: The jet stream is a high-speed wind current in the upper troposphere. It can influence weather patterns, but its movement alone does not explain the reducing rainfall pattern.

In conclusion, the primary reason for the reducing rainfall pattern when moving from the equator to the poles is the change in solar insolation. As the angle of sunlight decreases and the amount of solar radiation received reduces, there is less evaporation and moisture available for rainfall.

Explanation:
Buttress roots in tropical rainforests serve two main purposes:

1. Aeration of the soil: The buttress roots of trees in tropical rainforests are large, wide, and above-ground extensions of the trunk. These roots help to anchor the tree in the shallow, nutrient-poor soil of the rainforest. They create a wide base and provide stability to the tree, preventing it from toppling over in the strong winds and heavy rains that are common in tropical rainforest environments. The extensive network of buttress roots also helps to distribute the weight of the tree evenly, reducing the strain on individual roots.

2. Support and stability: The buttress roots of tropical rainforest trees act as a support system, preventing the tree from falling over. The soil in tropical rainforests is often shallow and nutrient-poor, making it difficult for trees to anchor themselves securely. The buttress roots, with their large surface area, help to stabilize the tree by providing additional support and anchorage. This is especially important in the dense, crowded conditions of the rainforest, where trees compete for sunlight and space.

3. Enhanced nutrient absorption: Although not mentioned in the given options, buttress roots also play a role in gathering more nutrients from the poor rainforest soil. The extensive surface area of the buttress roots increases the absorption capacity of the tree, allowing it to extract more nutrients from the soil. This is particularly important in tropical rainforests where the soil is often nutrient-deficient due to rapid leaching and decomposition.

In conclusion, buttress roots in tropical rainforests serve the dual purpose of providing stability and support to the trees, as well as enhancing nutrient absorption from the nutrient-poor soil. Therefore, the correct answer is option 'B' - 2 and 3 only.

Explanation:

Capacity of air to hold moisture and temperature:
- As the air gets warmer, it's capacity to hold moisture increases if all other things are constant.
- This is because warm air has more energy which allows it to hold more water vapor.

White trail left by jets and condensation of moisture:
- The white trail left by jets is due to the condensation of moisture from their engines.
- Jet engines produce water vapor as a byproduct, which then condenses into ice crystals in the cold atmosphere.

Cyclonic rainfall and meeting of warm and cold air:
- Cyclonic rainfall is caused in the meeting of warm and cold air.
- When warm and cold air masses meet, the warm air rises and cools, causing the moisture in the air to condense and form clouds. These clouds then produce rainfall.

Therefore, the correct answer is option 'A' as statements 1 and 2 are true, while statement 3 is false.

During the day, this happens.

• So, if you are facing the sea, the wind will strike your face and continue to land.
• During the night, this happens. So, if you are facing the sea, the wind will strike your back and continue to the sea.

Explanation:

The correct answer is option B: The Earth, in turn, radiates back solar insolation received from the Sun.

Reasoning:

The Earth receives solar insolation from the Sun in the form of electromagnetic radiation. This energy is absorbed by the Earth's atmosphere, land, and oceans. However, the Earth as a whole neither accumulates heat nor loses it due to solar insolation because it radiates back an equal amount of energy into space. This process is known as radiative balance or radiative equilibrium.

Key Points:
- Solar insolation refers to the amount of solar radiation received per unit area on the Earth's surface.
- The Earth's atmosphere plays a crucial role in regulating the amount of solar energy that reaches the Earth's surface. It absorbs some of the incoming solar radiation and reflects or scatters the rest.
- The absorbed solar energy heats up the Earth's atmosphere, land, and oceans. However, this heat is not accumulated indefinitely.
- The Earth radiates energy back into space in the form of longwave infrared radiation. This radiation is emitted by the Earth's surface, the atmosphere, and clouds.
- The rate of energy radiated by the Earth is equal to the rate of energy received from the Sun. This balance between incoming and outgoing radiation is necessary to maintain a stable temperature on Earth.
- If the Earth were to accumulate more energy than it radiates, the temperature would continually increase, leading to a runaway greenhouse effect. Conversely, if the Earth were to lose more energy than it receives, the temperature would continually decrease, resulting in a global cooling effect.
- The maintenance of radiative balance is crucial for the Earth's climate system. It ensures that the Earth's temperature remains relatively stable over long periods.

Therefore, the correct answer is option B: The Earth, in turn, radiates back solar insolation received from the Sun.

Tyndall effect can be observed when sunlight passes through the canopy of a dense forest. In the forest, mist contains tiny droplets of water, which act as particles of colloid dispersed in the air.

Extratropical Cyclones:
Extratropical cyclones, also known as mid-latitude or frontal cyclones, are large-scale low-pressure systems that occur in the middle and high latitudes outside the tropics. These cyclones are responsible for most of the weather patterns experienced in the middle latitudes, including strong winds, rain, and snow.

Important Features of Extratropical Cyclones:
1. They originate only over the seas or oceans: This statement is incorrect. While many extratropical cyclones do form over the seas or oceans, they can also form over land. Cyclones that form over land are known as continental cyclones. Therefore, this statement is not an important feature of extratropical cyclones.

2. They require a frontal system to get activated: This statement is correct. Extratropical cyclones are typically associated with the interaction of warm and cold air masses, resulting in the formation of a frontal system. The presence of a frontal system is necessary for the development and intensification of extratropical cyclones. Fronts are boundaries between air masses with different temperatures and densities, and the interaction between these air masses leads to the formation of the cyclone.

3. Since they can move only vertically above, they must be carried laterally by jet streams to be effective: This statement is incorrect. Extratropical cyclones are not limited to moving only vertically above. They are characterized by their cyclonic circulation, which involves both vertical and horizontal movement of air. While jet streams can influence the movement and intensity of extratropical cyclones, they are not required for their effectiveness.

Conclusion:
Out of the given statements, only statement 2 is an important feature of extratropical cyclones. These cyclones require a frontal system to get activated and are associated with the interaction of warm and cold air masses. They can form over both land and seas/oceans, and their movement is not limited to vertical displacement above. Therefore, the correct answer is option 'A' (2 only).

Factors that affect the temperature at a particular region include:

1. Circulation of planetary and local winds:
The circulation of winds plays a crucial role in determining the temperature of a region. The movement of air masses through the circulation of winds can bring warm or cold air to a particular area, thereby affecting its temperature. For example, the warm and dry winds blowing from the desert regions can increase the temperature in nearby areas, while the cool sea breeze can lower the temperature in coastal regions.

2. Altitude and terrain of the place:
Altitude and terrain have a significant impact on temperature. As we move higher in altitude, the temperature tends to decrease. This is because the air becomes thinner and cannot retain heat as effectively. Additionally, the presence of mountains or other geographical features can influence temperature patterns by blocking or diverting air masses, leading to variations in temperature.

3. Distance of the region from poles or equator:
The distance of a region from the poles or equator is a crucial factor in determining its temperature. The equatorial regions receive direct sunlight throughout the year, resulting in higher temperatures. On the other hand, the polar regions receive oblique sunlight, leading to lower temperatures. The regions located in between experience moderate temperatures.

4. Movement of ocean waves:
The movement of ocean waves, particularly ocean currents, can significantly influence the temperature of coastal regions. Ocean currents can transport warm or cold water from one region to another, thereby affecting the temperature of the coastal areas. For example, the Gulf Stream current brings warm water from the tropics to the eastern coast of North America, resulting in relatively higher temperatures in that region.

Therefore, the correct answer is option 'B' (1, 2, and 3 only). The circulation of winds, altitude and terrain, and the distance of the region from poles or equator are the factors that affect the temperature at a particular region. The movement of ocean waves, while important for coastal regions, is not a factor that affects the temperature at a broader regional scale.

Thunderstorms are formed because of intense convection on moist hot days. Convection refers to the transfer of heat through the movement of fluids, such as air or water. Thunderstorms are a type of weather phenomenon that involves the rapid upward movement of warm, moist air, which eventually leads to the formation of towering cumulonimbus clouds.

Here is a detailed explanation of why thunderstorms form due to intense convection on moist hot days:

1. Introduction to Thunderstorms:
- Thunderstorms are characterized by the presence of cumulonimbus clouds, which are large, dense, and vertically towering.
- These clouds are formed due to the rapid upward movement of warm, moist air.

2. Intense Convection:
- Thunderstorms are primarily formed due to intense convection, which occurs when there is a significant temperature difference between the surface and the upper atmosphere.
- On a hot and moist day, the surface temperature rises, leading to the heating of the lower layers of the atmosphere.
- This heating causes the air near the surface to become warmer and less dense, making it rise rapidly.

3. Updrafts and Downdrafts:
- As the warm air rises, it forms updrafts, which are powerful currents of air moving upward.
- These updrafts carry moisture and heat energy with them as they ascend.
- As the air rises higher into the atmosphere, it cools and condenses, forming cumulonimbus clouds.
- Within these clouds, the rising air cools further, and water droplets and ice crystals start to form, leading to the development of precipitation.

4. Thunderstorm Characteristics:
- Thunderstorms are often associated with heavy rainfall, lightning, strong winds, and sometimes hail.
- The rapid movement of air within the storm system creates strong updrafts and downdrafts, contributing to the formation of severe weather conditions.

5. Moisture Source:
- Moisture is a crucial ingredient for thunderstorm formation.
- On hot days, there is often an abundant supply of moisture available in the lower layers of the atmosphere, which can be provided by sources such as bodies of water, evaporation, or advection from other regions.

In conclusion, thunderstorms are formed due to intense convection on hot and moist days. The rapid upward movement of warm, moist air creates powerful updrafts within cumulonimbus clouds, leading to the formation of thunderstorms. These storms are characterized by heavy rainfall, lightning, and strong winds.

Explanation:

Statement 1: The air pressure is highest at sea level and decreases with height.

This statement is correct. The air pressure at sea level is the weight of the air above a unit area at sea level. As we move up in the atmosphere, the weight of the air decreases, and hence, the air pressure also decreases. Thus, air pressure is highest at sea level and decreases with height.

Statement 2: Low air pressure is generally associated with cloudy skies and wet weather.

This statement is also correct. Low air pressure is associated with unstable weather conditions and the formation of clouds. When the air pressure is low, the air rises, cools, and condenses to form clouds. The condensation of water vapor in the air leads to the formation of precipitation, which can result in wet weather.

Conclusion:

Both statements 1 and 2 are correct. The air pressure is highest at sea level and decreases with height. Low air pressure is associated with unstable weather conditions and the formation of clouds, which can lead to wet weather.

Movement of Inter-tropical convergence zone:
The movement of the Inter-tropical convergence zone (ITCZ) is one of the factors that affect the generation and flow of Equatorial Westerlies.

The ITCZ is a low-pressure belt that encircles the Earth near the equator. It is characterized by the convergence of trade winds from the Northern Hemisphere and Southern Hemisphere. The zone moves northward during summer in the Northern Hemisphere and southward during summer in the Southern Hemisphere.

1. During the summer in the Northern Hemisphere, the ITCZ moves northward, resulting in the convergence of trade winds from the Northern Hemisphere and the Equatorial Westerlies. This convergence leads to the generation of Equatorial Westerlies.

2. Similarly, during the summer in the Southern Hemisphere, the ITCZ moves southward, resulting in the convergence of trade winds from the Southern Hemisphere and the Equatorial Westerlies. This convergence also leads to the generation of Equatorial Westerlies.

Coriolis force caused due to the rotation of Earth:
The Coriolis force, which is caused due to the rotation of the Earth, is another factor that affects the generation and flow of Equatorial Westerlies.

The Coriolis force is an apparent force that deflects the motion of objects, including air masses, on the rotating Earth. In the Northern Hemisphere, the deflection is to the right, while in the Southern Hemisphere, it is to the left.

1. The Coriolis force deflects the trade winds from the Northern Hemisphere towards the right, resulting in the formation of Equatorial Westerlies.

2. In the Southern Hemisphere, the Coriolis force deflects the trade winds towards the left, also resulting in the formation of Equatorial Westerlies.

Both 1 and 2:
Therefore, both the movement of the Inter-tropical convergence zone and the Coriolis force caused due to the rotation of the Earth play a role in the generation and flow of Equatorial Westerlies. The movement of the ITCZ leads to the convergence of trade winds, while the Coriolis force deflects these winds to form the Equatorial Westerlies. Hence, option C, "Both 1 and 2," is the correct answer.

Not Related to Formation or Modification of Present Atmosphere

Differentiation is not related to the formation or modification of the present atmosphere.

Explanation:

Formation and modification of the present atmosphere involve various processes that have occurred over millions of years. Some of the significant processes that have led to the formation or modification of the atmosphere are:

1. Solar winds: Solar winds are streams of charged particles that originate from the sun. These solar winds have contributed to the formation of the atmosphere by stripping away the outer layer of the early atmosphere.

2. Degassing: Degassing refers to the release of gases from the Earth's interior. Volcanic eruptions and other tectonic activities have contributed to the release of gases such as carbon dioxide, nitrogen, and water vapor.

3. Photosynthesis: Photosynthesis is the process by which plants convert carbon dioxide and water into oxygen and organic compounds. This process has led to the increase in the concentration of oxygen in the atmosphere.

However, differentiation is not related to the formation or modification of the present atmosphere. Differentiation refers to the process by which the Earth's interior became separated into distinct layers, with the heaviest materials sinking to the core and the lighter materials rising to the surface. This process occurred early in the Earth's history, and it did not have a significant impact on the formation or modification of the atmosphere.

The correct answer is option 'D', None of the above. Let's discuss why.

1. They blow mainly in the Northern Hemisphere near the equator:
This statement is incorrect. The South-East trade winds do not blow mainly in the Northern Hemisphere near the equator. In fact, they blow primarily in the Southern Hemisphere near the equator. The trade winds are a global wind system that blows from the subtropical high-pressure belts towards the equator. In the Southern Hemisphere, the trade winds blow from the southeast towards the equator, while in the Northern Hemisphere, they blow from the northeast towards the equator.

2. The winds are deflected towards the East by the Coriolis Effect:
This statement is also incorrect. The South-East trade winds are not deflected towards the East by the Coriolis Effect. The Coriolis Effect is a phenomenon that is caused by the rotation of the Earth. It causes moving objects, including wind, to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. As a result, the South-East trade winds are actually deflected towards the West in the Southern Hemisphere, not towards the East.

In summary, both statements given about the South-East trade winds are incorrect. The trade winds blow primarily in the Southern Hemisphere near the equator and are deflected towards the West by the Coriolis Effect. Therefore, the correct answer is option 'D', None of the above.

Polar Vortex

The polar vortex is a persistent, large-scale cyclone that circles either of the planet's geographical poles. Here is a detailed explanation of what the polar vortex is:

Definition
The polar vortex is a low-pressure system that is located in the upper atmosphere, typically in the stratosphere, and is centered on the Earth's poles. It is strongest in the winter months and weakens or breaks down in the summer.

Nature
The polar vortex is a natural phenomenon that has always existed, but it has gained more attention in recent years due to its impact on weather patterns and extreme cold outbreaks in certain regions.

How It Forms
The polar vortex forms and is maintained by the temperature difference between the polar regions and the mid-latitudes. This temperature difference creates a strong wind pattern that circles the poles.

Impact on Weather
When the polar vortex weakens or shifts, it can lead to disruptions in the jet stream and result in extreme weather events such as cold outbreaks, heavy snowfall, and even heatwaves in some regions.

Conclusion
In conclusion, the polar vortex is a persistent, large-scale cyclone that plays a crucial role in shaping weather patterns around the world, particularly during the winter months. Understanding the polar vortex is essential for predicting and preparing for extreme weather events.