Which weather condition is associated with the presence of fine ash particles in the atmosphere?

The presence of fine ash particles in the atmosphere is primarily associated with volcanic ash. When a volcano erupts, it releases significant amounts of ash, which can be made up of tiny particles of glass, rock, and minerals. This ash can travel long distances, becoming a significant concern for aviation as it can impact aircraft engines and visibility.

In contrast, snow, heavy rain, and sandstorms do not involve volcanic ash. Snow consists of frozen water crystals, heavy rain involves liquid water droplets, and sandstorms are caused by wind lifting sand particles from the ground. Therefore, volcanic ash is the correct association for fine ash particles present in the atmosphere.