Q1.With reference to the ‘Polar Vortex’, consider the following statements:
- It is a large area of low pressure and cold air surrounding both of the Earth’s poles.
- The vortex weakens in summer and strengthens in winter.
- A strong polar vortex is usually associated with severe cold waves in the mid-latitudes of the Northern Hemisphere.
Which of the statements given above is/are correct?
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2, and 3
Correct Answer: A) 1 and 2 only
Explanation:
- Statement 1 is correct: The polar vortex is a wide expanse of swirling cold air that is parked in the polar regions. It exists at both the North and South Poles.
- Statement 2 is correct: The vortex is powered by the temperature difference between the poles and the equator. This difference is greatest during winter, causing the vortex to strengthen. In summer, the difference decreases, and the vortex weakens.
- Statement 3 is incorrect: A strong polar vortex keeps the cold air “bottled up” at the poles. It is a weak or “disturbed” polar vortex that allows cold arctic air to spill southward into mid-latitude regions like North America, Europe, and Asia, leading to extreme cold waves.
Q2.The phenomenon of ‘Sudden Stratospheric Warming’ (SSW) is most closely linked to which of the following atmospheric outcomes?
A) The intensification of the trade winds and El Niño.
B) The weakening and splitting of the Polar Vortex.
C) The rapid depletion of the Ozone layer in the Tropical Upper Troposphere.
D) The formation of tropical cyclones in the Bay of Bengal.
Correct Answer: B) The weakening and splitting of the Polar Vortex.
Explanation:
- Sudden Stratospheric Warming (SSW) occurs when large-scale atmospheric waves (Rossby waves) travel upward into the stratosphere and break, rapidly increasing the temperature in the polar stratosphere.
- This warming disrupts the circular flow of the polar vortex, causing it to slow down, shift off the pole, or even split into multiple smaller vortices.
- When the vortex splits or weakens, the jet stream becomes wavy (meridional flow), allowing frigid air to migrate toward lower latitudes.
Q3.Consider the following statements regarding the relationship between the Polar Vortex and the Jet Stream:
- The Polar Vortex is located in the Troposphere, while the Polar Front Jet Stream is located in the Stratosphere.
- A fast-moving Jet Stream acts as a barrier that prevents the Polar Vortex from moving southward.
- The “wavy” behavior of the Jet Stream is often a result of a weakened Polar Vortex.
Which of the statements given above are correct?
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2, and 3
Correct Answer: B) 2 and 3 only
Explanation:
- Statement 1 is incorrect: It is generally the opposite. The Polar Vortex is primarily a stratospheric phenomenon (though its influence extends downward), while the Polar Front Jet Stream is located at the top of the troposphere (the tropopause).
- Statement 2 is correct: When the jet stream is strong and stable, it acts as a boundary, trapping the cold air of the vortex in the Arctic.
- Statement 3 is correct: When the vortex weakens, the temperature gradient decreases, causing the jet stream to lose its “tightness” and become wavy. These waves are known as Rossby Waves, and their troughs bring arctic air deep into the mid-latitudes.
Q4.Which of the following best describes the ‘Arctic Oscillation’ (AO) in the context of the Polar Vortex?
A) A localized wind pattern over the Himalayan plateau affecting the Indian Monsoon.
B) A measure of the pressure difference between the Arctic and the mid-latitudes.
C) The seasonal migration of marine species due to warming Arctic waters.
D) The thermal expansion of the Arctic ice cap during the summer solstice.
Correct Answer: B) A measure of the pressure difference between the Arctic and the mid-latitudes.
Explanation:
- The Arctic Oscillation (AO) is an atmospheric index that is intrinsically linked to the strength of the polar vortex.
- Positive Phase (+AO): Higher pressure in mid-latitudes and lower pressure over the Arctic. This creates a strong jet stream and a stable polar vortex, keeping cold air in the north.
- Negative Phase (-AO): The pressure gradient weakens. The polar vortex becomes unstable, the jet stream becomes wavy, and cold arctic air is pushed toward the equator. This is typically when regions like India (northern parts), Europe, and the US experience “cold snaps.”
Q5.Consider the following statements regarding the impact of Climate Change on the Polar Vortex:
- Arctic Amplification (rapid warming of the Arctic) reduces the temperature gradient between the pole and the equator.
- A reduced temperature gradient tends to strengthen the Polar Vortex, making it more stable.
- Melting sea ice is theorized to contribute to more frequent disruptions of the stratospheric polar vortex.
Which of the statements given above are correct?
A) 1 and 2 only
B) 2 and 3 only
C) 1 and 3 only
D) 1, 2, and 3
Correct Answer: C) 1 and 3 only
Explanation:
- Statement 1 is correct: The Arctic is warming nearly four times faster than the rest of the globe. This “Arctic Amplification” narrows the temperature difference between the cold north and the warm tropics.
- Statement 2 is incorrect: A strong temperature gradient is what powers the vortex. Therefore, a reduced gradient actually weakens the vortex, making it more prone to wobbling or breaking.
