The Atmosphere Archives

21. Consider the following statements regarding ‘fronts’ : 1. The moveme

Consider the following statements regarding ‘fronts’ :

1. The movement of a front causes a slow change in weather in the area over which it moves.
2. Cold fronts are associated with thunderstorms.
3. Warm front is the boundary between an advancing mass of warm air where it is overriding and rising above a mass of colder air.

Which of the statements given above is/are correct ?

1 only

1 and 2 only

2 and 3 only

1, 2 and 3

This question was previously asked in

UPSC NDA-1 – 2024

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Statement 2 is correct. Cold fronts involve the rapid lifting of warm air by an advancing cold air mass, leading to steep pressure gradients and instability, which frequently results in the formation of cumulonimbus clouds and thunderstorms, heavy rain, and gusty winds. Statement 3 is correct. A warm front is defined as the boundary where an advancing mass of warm air overrides and rises above a colder air mass. The warm air, being less dense, slides up over the wedge of colder air. Statement 1 is incorrect. While warm fronts typically cause gradual and prolonged weather changes (like steady rain), cold fronts often bring about rapid and significant weather changes (sudden temperature drop, intense precipitation, thunderstorms). Thus, saying “slow change” for *all* fronts is incorrect.

Atmospheric fronts are the boundaries between air masses with different temperature, humidity, and density characteristics. Their passage is associated with significant weather changes. Cold fronts are generally steeper and move faster than warm fronts.

Other types of fronts include stationary fronts (where air masses meet but neither is strong enough to replace the other) and occluded fronts (formed when a cold front overtakes a warm front). Each type of front is associated with characteristic cloud formations, precipitation patterns, and temperature/pressure changes.

22. Snow, sleet and hail are the forms of

Snow, sleet and hail are the forms of

precipitation

condensation

transpiration

evaporation

This question was previously asked in

UPSC NDA-1 – 2022

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The correct answer is A) precipitation.

Precipitation is any form of water that falls from clouds and reaches the ground. This includes rain, snow, sleet, hail, and drizzle. Snow, sleet, and hail are specific forms of precipitation.

Condensation is the process by which water vapor in the air changes into liquid water or ice crystals (forming clouds). Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Evaporation is the process by which water changes from a liquid to a gas or vapor. None of these describe the forms of water *falling* to the ground.

23. Which one of the following is not a form of condensation ?

Which one of the following is not a form of condensation ?

Dew

Fog

Frost

Sleet

This question was previously asked in

UPSC NDA-1 – 2021

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Sleet is a form of precipitation consisting of ice pellets, often formed when snowflakes melt partially as they fall through a layer of warm air and then refreeze in a sub-freezing layer near the surface. While it involves freezing water, it is primarily a form of precipitation resulting from the freezing of raindrops or melted snow, not directly from the condensation of water vapor into a liquid or solid form on a surface or within the air mass like dew, fog, or frost.

Condensation is the process by which water vapor in the air changes into liquid water or ice. Forms of condensation include dew (liquid water on surfaces), fog (liquid water droplets suspended in air), mist (similar to fog but less dense), frost (ice formed directly from vapor deposition on surfaces below freezing), and clouds (liquid water droplets or ice crystals suspended in the atmosphere).

Precipitation includes various forms of water falling from clouds to the ground, such as rain, snow, sleet, and hail. Condensation is a necessary precursor for cloud formation and precipitation, but sleet itself is classified as a type of precipitation, not a form of condensation like dew or fog.

24. The composition of gases in exosphere is

The composition of gases in exosphere is

Helium and Hydrogen.

Neon and Oxygen.

Neon and Hydrogen.

Helium and Neon.

This question was previously asked in

UPSC NDA-1 – 2021

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The composition of gases in the exosphere is primarily Helium and Hydrogen.

The exosphere is the uppermost layer of Earth’s atmosphere. At these extremely high altitudes, the atmosphere is very thin, and the lightest gases, mainly hydrogen and helium, are the most abundant because gravity has less hold on them, and they can even escape into outer space.

Below the exosphere is the thermosphere, where lighter gases become increasingly dominant with altitude, but oxygen and nitrogen are still significant at lower thermospheric levels. In the exosphere, the gases are so sparse that particles travel long distances without colliding.

25. ‘Inversion of Rainfall” is associated with

‘Inversion of Rainfall” is associated with

Orographic rainfall

Convectional rainfall

Cyclonic rainfall (Tropical)

Cyclonic rainfall (Temperate)

This question was previously asked in

UPSC NDA-1 – 2019

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‘Inversion of Rainfall’ is associated with Orographic rainfall.

Inversion of rainfall refers to the phenomenon where, in mountainous regions, rainfall increases with altitude up to a certain height (the zone of maximum precipitation), but then decreases above that level. This pattern is typically observed in orographic rainfall, which occurs when moist air is forced to rise over a mountain barrier. As the air rises, it cools, leading to condensation and precipitation on the windward slopes. However, at very high altitudes, the amount of moisture in the air may decrease, temperatures become very low, and other factors limit further precipitation, causing the rainfall amount to decrease beyond the optimum level.

Convectional rainfall occurs due to vertical uplift of heated air, often leading to thunderstorms, and doesn’t typically exhibit this specific altitude-dependent inversion pattern across a mountain slope. Cyclonic rainfall (Tropical or Temperate) is associated with large-scale weather systems (low-pressure systems, fronts) where precipitation patterns are influenced by convergence and uplift over broader areas, not primarily by the forced ascent over a single mountain barrier which causes the distinct rainfall profile described as inversion.

26. Which one of the following is NOT true in reference to Air mass ?

Which one of the following is NOT true in reference to Air mass ?

Air mass forms either in tropical or in polar region

Air mass develops on continents as well as over ocean

Air mass develops in a cyclonic condition

Air mass changes the weather conditions

This question was previously asked in

UPSC NDA-1 – 2019

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It is NOT true that Air mass develops in a cyclonic condition.

An air mass is a large volume of air that has relatively uniform temperature and moisture characteristics throughout, acquired from its source region.
A) Air mass forms either in tropical or in polar region: True. Source regions are typically large, homogeneous areas like tropical oceans, polar continents, etc.
B) Air mass develops on continents as well as over ocean: True. Source regions can be continental (cA, cT) or maritime (mA, mT).
C) Air mass develops in a cyclonic condition: False. Cyclonic conditions involve convergence and uplift, leading to mixing and non-uniformity. Air masses form in areas of stable, stagnant, or slow-moving air, usually under high pressure (anticyclonic) conditions where the air resides long enough to take on the characteristics of the underlying surface.
D) Air mass changes the weather conditions: True. When an air mass moves from its source region to another area, it brings its characteristic temperature and moisture properties, influencing the weather of the new region.

Source regions for air masses are typically high-pressure areas because the air in such systems is stable and subsides, allowing it to remain over a region for sufficient time to acquire uniform properties. Low-pressure systems (cyclones) are dynamic zones of converging and lifting air, which are not conducive to the formation of homogeneous air masses. Instead, cyclones often form along the boundaries (fronts) between different air masses.

27. In which sphere of the atmosphere is harmful ultraviolet (UV) radiatio

In which sphere of the atmosphere is harmful ultraviolet (UV) radiation from the Sun absorbed ?

Mesosphere

Thermosphere

Troposphere

Stratosphere

This question was previously asked in

UPSC Geoscientist – 2024

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The atmosphere is composed of several layers, each with distinct characteristics regarding temperature, composition, and phenomena. The absorption of harmful ultraviolet (UV) radiation from the Sun primarily occurs in a specific layer.

– The **Stratosphere** contains the ozone layer (O₃). Ozone molecules are highly effective at absorbing UV-B and UV-C radiation from the sun, preventing most of it from reaching the Earth’s surface.
– The Mesosphere is above the stratosphere, where most meteors burn up.
– The Thermosphere is the outermost layer, where temperature rises sharply due to absorption of high-energy radiation, but it’s not the primary layer for absorbing harmful UV-B/C.
– The Troposphere is the lowest layer, where weather occurs, and it absorbs very little UV radiation.

The absorption of UV radiation by the ozone layer in the stratosphere is crucial for protecting life on Earth from the damaging effects of high-energy UV radiation, such as skin cancer and damage to plant life.

28. Consider the following combinations of lapse rate in relation to atmos

Consider the following combinations of lapse rate in relation to atmospheric region :

1. Troposphere : Negative lapse rate
2. Stratosphere : Negative lapse rate
3. Mesosphere : Negative lapse rate
4. Thermosphere : Positive lapse rate

How many of the combinations given above is/are correct ?

This question was previously asked in

UPSC Geoscientist – 2024

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Lapse rate refers to the rate at which temperature changes with altitude in the atmosphere. A positive lapse rate means temperature decreases with increasing altitude. A negative lapse rate (also known as an inversion) means temperature increases with increasing altitude. We need to examine the temperature profile of each atmospheric layer.

1. **Troposphere:** Temperature generally decreases with altitude (positive lapse rate). Statement 1 is incorrect.
2. **Stratosphere:** Temperature increases with altitude due to the absorption of UV radiation by the ozone layer (negative lapse rate). Statement 2 is correct.
3. **Mesosphere:** Temperature decreases with altitude (positive lapse rate), reaching the coldest temperatures in the atmosphere at the mesopause. Statement 3 is incorrect.
4. **Thermosphere:** Temperature increases significantly with altitude due to the absorption of high-energy solar radiation (negative lapse rate/temperature increasing with height). Statement 4 states positive lapse rate, which is incorrect.

The atmospheric layers are defined based on temperature changes with altitude. The boundaries between layers (tropopause, stratopause, mesopause) are where the temperature trend reverses. Only the Stratosphere and Thermosphere exhibit temperature increases with altitude.

29. Which one of the following zones of atmosphere is the farthest from th

Which one of the following zones of atmosphere is the farthest from the earth surface?

Stratosphere

Mesosphere

Ionosphere

Troposphere

This question was previously asked in

UPSC Geoscientist – 2023

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The Ionosphere is the farthest zone from the Earth’s surface among the options provided.

The layers of the atmosphere from Earth’s surface upwards are Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. The Ionosphere is not a distinct layer but a region within the Thermosphere (and parts of the Mesosphere and Exosphere) characterized by ionization due to solar radiation. Among the given options (Stratosphere, Mesosphere, Ionosphere, Troposphere), the Ionosphere is situated highest above the Earth’s surface, being part of the Thermosphere which is above the Mesosphere.

The exosphere is the outermost layer, extending into space. The Thermosphere, where the Ionosphere is located, is known for its high temperatures (though not felt as heat due to low density) and is where phenomena like the aurora occur.

30. The uplift mechanism that takes place when lighter warm moist air mass

The uplift mechanism that takes place when lighter warm moist air mass rises after encountering a colder and denser air mass causes

conventional precipitation

frontal precipitation

cyclonic precipitation

orogenic precipitation

This question was previously asked in

UPSC Geoscientist – 2023

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The correct answer is (B) frontal precipitation.

Frontal precipitation occurs when a warmer, lighter air mass is forced to rise over a colder, denser air mass along a weather front. As the warm, moist air rises, it cools, condenses, and forms precipitation. This uplift mechanism is characteristic of frontal systems like warm fronts and cold fronts.

Conventional precipitation results from the uplift of warm, moist air due to surface heating, often leading to thunderstorms. Cyclonic precipitation is associated with low-pressure systems (cyclones), which often involve frontal systems but the term “cyclonic” refers to the overall system’s circulation. Orogenic precipitation occurs when air is forced to rise over mountains (orographic lift). The description specifically matches the interaction of distinct air masses at a front.