Climatology: UPSC Previous Year Questions (Geography)

Explanation

Statement 1 is correct: The primary reason the westerlies in the Southern Hemisphere are stronger and more persistent than in the Northern Hemisphere is because the Southern Hemisphere has significantly less landmass (about 20% land and 80% water), whereas the Northern Hemisphere has 40% land and 60% water. The vast oceans in the Southern Hemisphere allow westerly winds to move with minimal obstruction, making them stronger and more persistent. In contrast, larger landmasses in the Northern Hemisphere create friction and disrupt wind flow.

Statement 2 is incorrect: The Coriolis force acts equally in both hemispheres at the same latitude as it depends on the Earth’s rotation and the latitude. It does not make the westerlies stronger in one hemisphere over the other. The main reason for the difference is the land-sea distribution. The Coriolis force is stronger near the poles and weaker at the equator, but it does not explain the difference in strength of the westerlies between the two hemispheres.

Explanation

Statement 1 is correct: The African and Eurasian desert belt (Sahara, Arabian, Thar, Gobi) lies in the sub-tropical high-pres-sure zone (20°-30° latitudes). In this region, descending dry air from the Hadley Cell suppresses cloud formation and rainfall, creating arid conditions. This becomes the main reason for the formation of these deserts.

Statement 2 is incorrect: Warm ocean currents increase evaporation followed by humidity, leading to higher rainfall in coastal areas rather than desert formation. Deserts are mainly found near cold ocean currents (e.g., the Atacama Desert near the Peru Current, the Namib Desert near the Benguela Current), which cool the air and reduce its moisture-holding capacity, causing dry conditions. Moreover, many deserts in this belt are landlocked, far from direct oceanic influence.

Explanation

Statement 1 is correct: The lower stratosphere is mostly free from clouds and water vapor, as most weather phenomena occur in the troposphere below. This impacts the clear air conditions, making it ideal for jet aircraft to fly smoothly.

Statement 2 is correct: The stratosphere is a stable layer with no vertical air movements like convection currents. In contrast, the troposphere experiences turbulence due to rising and falling air masses. The absence of vertical winds in the lower stratosphere ensures a steady flight for jet aircraft.

Explanation

Mangroves function as a safety hedge due to their extensive root systems. These roots act as a natural barrier, protecting coastlines from erosion and the impact of strong waves during storms, cyclones, and tsunamis. The dense network of roots helps to dissipate the energy of waves, reducing their im-pact on the shoreline.