What meteorological condition traps pollutants near the surface, increasing concentrations?

What meteorological condition traps pollutants near the surface, increasing concentrations?

• A. Thermal inversion
• B. Strong winds
• C. Heavy rainfall
• D. High humidity with active mixing

Answer: (A)

Temperature inversions trap pollutants near the surface by creating a stable layer of warm air above cooler air, which acts like a lid and blocks vertical air movement. Emissions released at ground level can’t mix upward, so they accumulate and concentrations rise, especially during calm conditions or in valleys where air sits stagnant. In contrast, strong winds promote dispersion, heavy rainfall clears pollutants from the air, and high humidity with active mixing tends to dilute and mix pollutants rather than trap them. Therefore, this condition increases near-surface pollutant concentrations.

Temperature inversions trap pollutants near the surface by creating a stable layer of warm air above cooler air, which acts like a lid and blocks vertical air movement. Emissions released at ground level can’t mix upward, so they accumulate and concentrations rise, especially during calm conditions or in valleys where air sits stagnant. In contrast, strong winds promote dispersion, heavy rainfall clears pollutants from the air, and high humidity with active mixing tends to dilute and mix pollutants rather than trap them. Therefore, this condition increases near-surface pollutant concentrations.