Which stability class is associated with good dispersion of pollutants?

Class D, associated with unstable atmospheric conditions, is linked to good dispersion of pollutants. In unstable atmospheres, air tends to rise, especially during the day when solar heating occurs. This rising motion promotes vertical mixing, which helps disperse pollutants more effectively.

In Class D conditions, the atmosphere's instability facilitates a more vigorous turbulent vertical movement. This increased turbulence breaks up and dilutes the pollutant concentration, allowing for better dispersion over larger areas. The rising warm air reduces the potential for pollutant accumulation at ground level, making it a favorable condition for minimizing air quality impacts.

In contrast, stability classes such as A and B indicate stable conditions, where vertical mixing is greatly limited, leading to poor dispersion of pollutants. Class C represents neutral stability, which is better than stable but not as conducive to dispersion as unstable conditions. Therefore, Class D is specifically associated with optimal pollutant dispersion due to its inherent characteristic of promoting a more dynamic and turbulent atmosphere.