Urban heat island effect – UGC NET Question

Urban heat islands occur when built-up surfaces absorb and re-radiate more heat than vegetated rural landscapes. Concrete, asphalt and buildings store heat, while reduced vegetation lowers cooling from evapotranspiration. Waste heat from vehicles, air-conditioners and industry further raises temperatures. As a result, cities are often several degrees warmer than nearby rural areas, especially at night, which matches the description in option B.

Option A:
Option A is incorrect since it reverses the observed pattern; rural areas are generally cooler, not warmer, at night. Their vegetation and open spaces allow more rapid cooling.

Option B:
Option B is correct because it identifies both the temperature difference and the main causes. It links warmer cities to material properties and anthropogenic heat, which is how climatologists define urban heat islands.

Option C:
Option C is incorrect because tall buildings can also trap heat and reduce wind flow. Shade helps in the daytime, but overall urban form still tends to raise average temperatures.

Option D:
Option D is incorrect as rainfall patterns are influenced by many factors. Population density alone does not explain the heat island effect, which is specifically about temperature.