Advection is the horizontal transport of air pollutants by the wind.

Deposition is the process by which air pollutants are removed from the atmosphere and deposited on the ground or water.

Diffusion is the process by which air pollutants spread out in the atmosphere due to random molecular motion.

Convection is the vertical transport of air pollutants by rising and sinking air currents.

Deposition velocity is the rate at which air pollutants are deposited on the ground or water.

Surface roughness is the primary factor that determines the deposition velocity of air pollutants.

Pollutant concentration is the term used to describe the concentration of air pollutants at a given location.

Vehicle emissions are the primary source of air pollution in urban areas.

Agricultural emissions are the primary source of air pollution in rural areas.

Atmospheric chemistry is the term used to describe the process by which air pollutants are transformed into different chemical species in the atmosphere.

Oxidation is the primary type of photochemical reaction that occurs in the atmosphere.

Heterogeneous reactions are the process by which air pollutants are removed from the atmosphere by chemical reactions.

Homogeneous reactions are the process by which air pollutants are removed from the atmosphere by chemical reactions that occur in the gas phase.

Heterogeneous reactions are the process by which air pollutants are removed from the atmosphere by chemical reactions that occur on the surface of particles.

Heterogeneous reactions are the process by which air pollutants are removed from the atmosphere by chemical reactions that occur in the liquid phase.