UGC NET Questions (Paper – 1)

Thermal inversion occurs when a layer of warm air overlays cooler air near the ground, suppressing vertical mixing. Under such stable conditions, pollutants emitted at the surface cannot disperse upward easily. As emissions continue, their concentration builds up close to the ground, creating smog and health hazards. Therefore, the key environmental consequence of thermal inversion in cities is the trapping of pollutants and deterioration of air quality, as stated in Option B.

Option A:
Option A is incorrect because thermal inversion reduces, rather than enhances, vertical mixing. The atmosphere becomes stable, so pollutants remain trapped instead of being carried away.

Option B:
Option B is correct since it describes the accumulation of pollutants near ground level when inversion prevents upward dispersion. This build-up leads to smog, reduced visibility and health problems.

Option C:
Option C is incorrect as nothing in a thermal inversion makes pollutants disappear automatically. In fact, the stable conditions allow them to persist and accumulate.

Option D:
Option D is incorrect because thermal inversion itself does not guarantee rainfall. While rain can help wash out pollutants, inversion episodes are often associated with dry, stagnant conditions.