Why can fog remain for longer during a temperature inversion?

Correct answer: Cold moist air is trapped below and mixing decreases

Correct answer: A. Normally, air near the ground may mix with air above it as temperature changes with height. During a temperature inversion, a layer of relatively warmer air lies above colder air near the surface. The warmer layer acts like a lid and strongly limits vertical mixing. If the lower air is moist and already contains fog droplets, it cannot disperse or warm easily. The droplets therefore remain suspended for a longer time, particularly when wind and sunlight are weak. A is correct because it identifies both trapping of cold moist air and reduced mixing. B is wrong because the inversion places warmer air above, not necessarily rapidly falling below. C is physically unrelated; water vapour does not become stone. D is wrong because the upper layer suppresses exchange rather than removing every droplet. Memory cue: inversion is a lid that traps cool, moist, polluted air near the ground.