The Atmosphere

In the Hadley cell thermal circulation, air rises up and finally descends at

[amp_mcq option1=”intertropical convergence zone” option2=”doldrums” option3=”subtropical high-pressure cells” option4=”equatorial troughs” correct=”option3″]

The correct answer is C) subtropical high-pressure cells.

The Hadley cell is a large-scale atmospheric circulation pattern that dominates the tropical atmosphere. Warm, moist air rises at the Intertropical Convergence Zone (ITCZ), located near the equator, driven by intense solar heating (creating a low-pressure area). This rising air cools, loses moisture (leading to tropical rainfall), and then flows poleward at high altitudes. Around 30 degrees latitude North and South, the air cools further, becomes denser, and descends towards the surface. This descending air is dry and leads to high-pressure areas known as the subtropical high-pressure cells. This descent inhibits cloud formation, resulting in clear skies and arid conditions often associated with major deserts found around these latitudes.

The Doldrums refer to the low-pressure region near the equator associated with the ITCZ, where air rises. Equatorial troughs are also low-pressure regions around the equator. Air rises, not descends, in these regions.

Consider the following constituent gases of the atmosphere :

• 1. Argon
• 2. Neon
• 3. Helium
• 4. Carbon dioxide

Which one of the following is the correct ascending sequence of the above gases in terms of the volume percentage?

[amp_mcq option1=”1-3-2-4″ option2=”1-4-2-3″ option3=”4-2-3-1″ option4=”2-4-1-3″ correct=”option4″]

The question asks for the correct ascending sequence of atmospheric gases by volume percentage. Let’s list the approximate volume percentages of the given gases in dry air:
1. Argon (Ar): ~0.93%
2. Neon (Ne): ~0.0018%
3. Helium (He): ~0.0005%
4. Carbon dioxide (CO₂): ~0.04% (This value can slightly vary depending on the source/year, but its relative position is stable).
The correct ascending order by volume percentage is Helium (3) < Neon (2) < Carbon dioxide (4) < Argon (1). This corresponds to the sequence 3-2-4-1. Looking at the options provided: A) 1-3-2-4 (Ar, He, Ne, CO2) - Incorrect B) 1-4-2-3 (Ar, CO2, Ne, He) - This sequence (0.93%, 0.04%, 0.0018%, 0.0005%) represents the correct *descending* order of the gases. C) 4-2-3-1 (CO2, Ne, He, Ar) - Incorrect D) 2-4-1-3 (Ne, CO2, Ar, He) - Incorrect Based on standard scientific values, none of the options represent the correct ascending sequence (3-2-4-1). However, option B presents the correct descending sequence (1-4-2-3). It is highly probable that there is an error in the question asking for "ascending" instead of "descending", or a misprint in the options. Given that a forced choice from the options is required and B is the correct descending order, it is often the case in such flawed questions that the option matching the reverse order is the intended answer due to a mistake in the question phrasing. Assuming this likely error, we select B.

– The major components of dry air are Nitrogen (~78%), Oxygen (~21%), and Argon (~0.93%).
– Carbon dioxide, Neon, and Helium are trace gases, present in much smaller quantities.
– The order of abundance for the given gases is Argon > Carbon dioxide > Neon > Helium.

The percentages of atmospheric gases are generally constant in the lower atmosphere, except for variable gases like water vapor and carbon dioxide. The exact percentage of CO2 has been increasing due to human activities, but its relative abundance compared to Ar, Ne, and He remains in the same order.

Which of the following causes adiabatic temperature changes in atmosphere?

[amp_mcq option1=”Deflection and advection” option2=”Latent heat of condensation” option3=”Expansion and compression of the air” option4=”Partial absorption of solar radiation by the atmosphere” correct=”option3″]

Adiabatic temperature changes occur when the temperature of an air parcel changes due to expansion or compression without any heat exchange with its surroundings. When air rises, it expands due to lower atmospheric pressure, and this expansion causes it to cool (adiabatic cooling). When air sinks, it is compressed by higher pressure, and this compression causes it to warm (adiabatic warming).

Adiabatic processes involve temperature changes caused by work done during expansion or compression of air, not by heat transfer.

Deflection and advection involve horizontal air movement. Latent heat exchange (like condensation or evaporation) involves the release or absorption of heat, making the process non-adiabatic. Absorption of solar radiation is a form of heat transfer.