How does an inversion affect vertical mixing and weather?

• A. Temperature increases with height in an inversion, suppressing convection and trapping pollutants, fog, or low clouds near the ground.
• B. Temperature decreases with height in an inversion, enhancing mixing.
• C. It triggers widespread thunderstorms.
• D. It raises surface temperatures by warming the ground.

Answer: (A)

An inversion creates a stable layer in which temperature increases with height, instead of decreases. This stability means buoyant air parcels don’t rise easily, so vertical mixing is greatly suppressed. With mixing reduced, pollutants, smoke, and moisture tend to remain near the surface, leading to haze, and often fog or low clouds forming at ground level. Weather is typically stagnant near the surface—calm conditions with little vertical development and limited thunderstorm activity—because the “lid” of warmer air above prevents air from rising. In short, temperature increasing with height in an inversion suppresses convection and traps pollutants and moisture near the ground, producing fog or low clouds.