How does wet deposition differ from dry deposition?

Wet deposition and dry deposition are two processes through which pollutants and other substances are transferred from the atmosphere to the Earth's surface. The distinction lies primarily in the nature of the medium through which these substances are deposited.

The correct choice highlights that dry deposition involves the settling of solid particles—such as dust, smoke, and other particulates—when there is no precipitation, whereas wet deposition includes both liquid (like rain or snow) and solid forms (like aerosol particles that are captured by raindrops). This means that wet deposition is characterized by its dependence on moisture in the atmosphere, which facilitates the capture and removal of atmospheric pollutants from the air.

For instance, during a rainstorm, rain droplets can collect and remove pollutants from the air, an example of wet deposition. In contrast, dry deposition processes occur continuously and do not rely on precipitation; they often happen through gravity settling or adherence of particles to surfaces.

Understanding this distinction is vital for comprehending broader environmental processes, such as the cycling of nutrients and the effects of acid rain, which is a form of wet deposition. The other options do not suitably define the two processes, reinforcing the significance of option B.