How does the molecular weight of a COTA affect its dispersion?

The correct choice highlights an important concept in atmospheric dispersion related to the behavior of substances based on their molecular weight. Heavier materials, such as certain gases or aerosols, tend to have lower buoyancy in the atmosphere. This means that they are less likely to rise significantly and thus are often confined to lower altitudes or areas close to their source.

In many cases, heavier materials are influenced more by gravitational settling than by atmospheric turbulence, which can limit their dispersion in the surrounding air. As a result, these heavier particles may not mix or spread out as effectively as lighter substances. Air flows and turbulence may not provide enough energy to lift them into higher layers of the atmosphere, leading to poorer dispersion.

On the other hand, lighter materials tend to have greater buoyancy and can rise more easily, promoting more effective mixing and dispersion. The comparison emphasizes how molecular weight plays a crucial role in the behavior of substances in the atmosphere, which is fundamental for understanding dispersion patterns and potential impacts of various materials released into the environment.