What characteristic is primarily affected by higher density differences in atmospheric dispersion?

Higher density differences in atmospheric dispersion primarily affect concentration distribution because they lead to variations in how pollutants or dispersants are spread throughout the atmosphere. When there is a significant difference in density between two air masses, such as warm air and cool air, this creates buoyancy effects that alter how concentrations of released materials are layered or stratified in the atmosphere.

In a situation where the density difference is pronounced, lighter air can rise, leading to a more pronounced stratification and separation of various concentrations of gases or aerosols. This stratification impacts how pollutants disperse over distance and height in the atmosphere, significantly influencing the observed concentration distribution at various altitudes and distances from the source of emission.

While diffusion rate plays a role in how substances mix in the atmosphere, it is primarily the density differences that dictate how concentration gradients develop and behave over time. Flow patterns can also be influenced by density differences but are typically more related to larger-scale atmospheric convection. Mixing height refers to the vertical extent of turbulence in the atmosphere, which is generally influenced by other factors such as surface heating and stability rather than density differences alone. Hence, the primary impact of higher density differences is seen in the way concentrations of materials are distributed in the environment.