The Atmosphere

31. Which one of the following is not correct in the context of daytime he

Which one of the following is not correct in the context of daytime heating experienced on the Earth?

The highest daytime temperatures usually occur several hours after the time of maximum solar input
Equilibrium between incoming and outgoing radiation occurs about an hour and a half after sunset
The extent of daily lag in maximum temperature varies
Presence of vegetation cover reduces the maximum temperature
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UPSC Geoscientist – 2022
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Equilibrium between incoming and outgoing radiation, leading to maximum temperature, occurs when the rate of energy gain equals the rate of energy loss. During the day, incoming solar radiation exceeds outgoing radiation. Maximum temperature is reached when the net radiation balance becomes zero or slightly negative, typically in the mid-afternoon, several hours *after* solar noon (maximum solar input). After sunset, there is no incoming solar radiation, and the Earth continues to lose radiation, so outgoing radiation significantly exceeds incoming (zero). Equilibrium (net radiation=0) does *not* occur after sunset; the surface cools.
– There is a lag between the time of maximum solar radiation input (solar noon) and the time of maximum daily temperature due to the heat capacity of the surface and atmosphere.
– Maximum temperature occurs when the net energy balance transitions from positive (energy gain) to negative (energy loss). This transition point usually happens a few hours after maximum solar input and *before* sunset.
– After sunset, the net radiation balance is negative, and the surface cools.
The duration of the temperature lag (C) is influenced by factors like wind speed (mixing), cloud cover (insulation), humidity (evaporative cooling, water vapour greenhouse effect), and the thermal properties of the surface material. Vegetation cover (D) promotes evapotranspiration, which consumes energy (latent heat), thus reducing the energy available for sensible heating and lowering maximum surface and air temperatures.

32. The most significant ‘variable gases’ in the atmosphere are

The most significant ‘variable gases’ in the atmosphere are

oxygen and carbon dioxide
carbon dioxide and nitrogen
water vapour and carbon dioxide
water vapour and oxygen
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Variable gases in the atmosphere are those whose concentrations change significantly over time and space. Water vapour (H2O) is the most variable gas, with concentrations varying widely depending on temperature, location, and weather conditions. Carbon dioxide (CO2) is also a variable gas, with seasonal cycles and significant long-term increase due to human activities. Both are major greenhouse gases.
– Nitrogen (N2) and oxygen (O2) are the most abundant gases but are considered permanent or fixed gases because their global concentrations are relatively constant (around 78% N2 and 21% O2).
– Variable gases like water vapour, carbon dioxide, methane, and ozone exist in much smaller concentrations but play crucial roles in atmospheric processes, particularly climate and weather.
Water vapour is the most potent greenhouse gas, although its concentration is highly variable. Carbon dioxide is a less potent greenhouse gas molecule-for-molecule than some others (like methane) but its higher concentration and long atmospheric lifetime make it a primary driver of current climate change.

33. Which one among the following statements is NOT correct?

Which one among the following statements is NOT correct?

The troposphere is lower at high latitudes than low latitudes
The north-south temperature gradients are much steeper in winter
The strongest horizontal temperature gradients are in middle latitudes in both summer and winter
The north-south temperature gradient are much steeper in summer
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UPSC Geoscientist – 2021
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The correct answer is The north-south temperature gradient are much steeper in summer.
The north-south temperature gradient refers to the change in temperature with latitude. This gradient is much steeper in winter than in summer. In winter, the high latitudes receive very little or no solar radiation, leading to very cold temperatures, while the low latitudes remain relatively warm. This creates a large temperature contrast. In summer, high latitudes receive much more solar radiation (long daylight hours), warming them significantly, which reduces the temperature difference between high and low latitudes, making the gradient less steep.
Statements A, B, and C are correct. The troposphere is indeed thinner at the poles (high latitudes) and thicker at the equator (low latitudes) due to temperature differences and convective activity. The north-south temperature gradients are much steeper in winter (as explained above), and the strongest horizontal temperature gradients are found in the middle latitudes in both seasons, where polar and tropical air masses interact, leading to frontal systems and strong winds like the jet stream.

34. Temperature inversion most frequently occurs in:

Temperature inversion most frequently occurs in:

Lower Troposphere
Upper Troposphere
Lower Stratosphere
Upper Stratosphere
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The correct answer is Lower Troposphere.
Temperature inversion occurs when the temperature increases with increasing height in a layer of the atmosphere, which is the reverse of the normal decrease in temperature with height in the troposphere (lapse rate). Inversions most frequently occur near the Earth’s surface (surface inversions) or at relatively low altitudes, typically within the lower troposphere. These inversions can be caused by radiative cooling of the surface at night, the advection of warm air over a cold surface, or the subsidence of air.
The stratosphere is characterized by a temperature increase with height due to the absorption of ultraviolet radiation by the ozone layer. While this is a normal temperature profile for the stratosphere, the term “temperature inversion” usually refers to a layer within the troposphere or lower atmosphere where the temperature profile is inverted compared to the standard tropospheric lapse rate.

35. Which one among the following has the highest concentration in the

Which one among the following has the highest concentration in the atmosphere?

Argon
Carbon dioxide
Neon
Methane
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The correct answer is Argon.
While Nitrogen (~78%) and Oxygen (~21%) are the most abundant gases in the atmosphere, among the options provided, Argon has the highest concentration, making up about 0.93% of the dry atmosphere.
The concentrations of the other gases listed are significantly lower: Carbon dioxide is approximately 0.04%, Neon is about 0.0018%, and Methane is around 0.00018%.

36. Consider the following statements : 1. Hadley cells are key to under

Consider the following statements :

  • 1. Hadley cells are key to understanding the wind patterns of Earth.
  • 2. Hadley cells are formed because the Equator is heated more strongly by the Sun than other places, creating thermal circulations.

With regard to the statements given above, which of the following is correct ?

Both the statements are correct and statement 2 is the correct explanation of statement 1.
Both the statements are correct, but statement 2 is <i>not</i> the correct explanation of statement 1.
Statement 1 is correct, but statement 2 is false.
Statement 1 is false, but statement 2 is correct.
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Statement 1 is correct: Hadley cells are fundamental atmospheric circulation patterns in the tropics and are essential for understanding the global distribution of pressure belts and wind patterns like the trade winds and the intertropical convergence zone (ITCZ). Statement 2 is correct: Hadley cells are indeed formed due to the differential heating of the Earth’s surface. The equatorial region receives the most direct solar radiation, causing air to heat up, become less dense, and rise (convection). This rising warm air then flows poleward at high altitudes, cools, sinks around 30 degrees latitude, and returns towards the equator as surface winds (trade winds), completing the circulation loop. This thermal driving force directly explains the formation and function of Hadley cells, which, in turn, dictates tropical wind patterns. Thus, statement 2 is the correct explanation for statement 1.
Hadley cells are part of the general atmospheric circulation model, driven by latitudinal variations in solar radiation.
Beyond the Hadley cells (0-30 degrees), there are also Ferrel cells (30-60 degrees) and Polar cells (60-90 degrees), which contribute to the global pattern of atmospheric circulation and winds. However, the Hadley cells are the most thermally direct and dominant circulation feature in the tropics.

37. Which of the following statements about inversion of temperature is/ar

Which of the following statements about inversion of temperature is/are correct?
1. Temperature increases with increasing altitude.
2. A long winter night with clear skies is an ideal situation.
3. It is a short term phenomenon and is common all over the globe except at the poles.
Select the correct answer using the code given below:

1 and 2 only
2 and 3 only
1 only
1, 2 and 3
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UPSC CDS-2 – 2022
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The correct answer is A because statements 1 and 2 are correct regarding the conditions and nature of temperature inversion, while statement 3 contains an incorrect generalization about its occurrence at the poles.
– Statement 1: Temperature inversion is a phenomenon where temperature increases with increasing altitude in a layer of the atmosphere, contrary to the normal decrease (lapse rate) in the troposphere. Thus, this statement correctly describes the core characteristic of inversion.
– Statement 2: Ideal conditions for surface temperature inversion include a long winter night (allowing for maximum radiative cooling of the surface), clear skies (enhancing outgoing radiation and preventing atmospheric mixing), and calm air (preventing mixing of cold air near the surface with warmer air above).
– Statement 3: Temperature inversion is indeed a short-term phenomenon and is common in many parts of the world. However, it is not necessarily absent at the poles; strong and prolonged temperature inversions can occur in polar regions, especially during the long polar night, due to intense radiative cooling of the ice and snow surface.
Temperature inversions trap pollutants near the surface and can lead to severe air pollution episodes. They can be classified based on their formation mechanism, such as radiation inversion (surface cooling), advection inversion (warm air flowing over cold surface), frontal inversion (warm air overriding cold air), and mechanical inversion (subsidence).

38. Most ozone gas (about 90%) is located in the atmospheric layer of

Most ozone gas (about 90%) is located in the atmospheric layer of

ionosphere
troposphere
stratosphere
mesosphere
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UPSC CDS-2 – 2017
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The correct option is C) stratosphere.
The vast majority of ozone gas (approximately 90%) is concentrated in the stratosphere, forming the ozone layer. This layer is crucial for absorbing most of the Sun’s harmful ultraviolet (UV) radiation. A smaller amount of ozone exists in the troposphere, where it acts as a pollutant and a greenhouse gas.
The atmosphere is divided into several layers: troposphere (lowest), stratosphere, mesosphere, thermosphere, and exosphere. The ionosphere is a region within the thermosphere and exosphere where gases are ionized by solar radiation. Ozone formation and destruction primarily occur in the stratosphere.

39. Which of the following statements concerning atmosphere of the Earth a

Which of the following statements concerning atmosphere of the Earth are correct?

  • 1. In stratosphere, temperature increases with altitude.
  • 2. In mesosphere, temperature decreases with altitude.
  • 3. The lowest temperature of the atmosphere is recorded in the upper part of mesosphere.
  • 4. Tropopause is an isothermal zone.

Select the correct answer using the code given below.

1 and 2 only
1, 2 and 3 only
3 and 4 only
1, 2, 3 and 4
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UPSC CDS-2 – 2016
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Statements 1, 2, and 3 regarding the Earth’s atmosphere are correct.
Statement 1 is correct: In the stratosphere, temperature increases with altitude due to the absorption of ultraviolet radiation by the ozone layer. Statement 2 is correct: In the mesosphere, temperature decreases sharply with altitude, reaching very low temperatures at its upper boundary. Statement 3 is correct: The mesopause, located at the top of the mesosphere, is the coldest region of the Earth’s atmosphere. Statement 4 is generally considered incorrect: The tropopause is the boundary zone between the troposphere and stratosphere where the temperature lapse rate changes significantly; it’s not a thick isothermal layer, although temperature changes minimally with height within the boundary itself compared to the layers above and below.
The atmosphere’s temperature profile varies with altitude through its different layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer exhibits distinct temperature gradients driven by different physical processes.

40. Which one of the following statements about the Coriolis force is not

Which one of the following statements about the Coriolis force is not correct ?

It is maximum at the Poles.
It is absent at the Equator.
It deflects the wind to the right direction in the southern hemisphere.
It deflects the wind to the right direction in the northern hemisphere.
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UPSC CDS-1 – 2021
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The statement “It deflects the wind to the right direction in the southern hemisphere” is not correct.
The Coriolis force deflects moving objects (like wind and ocean currents) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
The Coriolis force is zero at the Equator and maximum at the Poles, and its magnitude increases with the speed of the moving object. It is an apparent force resulting from the Earth’s rotation. The correct statement for the Southern Hemisphere would be that it deflects wind to the left.
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