What defines fog in meteorological terms?

Fog is specifically defined as a suspension of tiny water droplets in the air that are at or near the ground level, leading to reduced visibility. This condition occurs when air becomes saturated with moisture, causing water vapor to condense into small droplets. These droplets hang in the atmosphere, creating a cloud-like phenomenon right at the surface.

Understanding fog in this context highlights its unique characteristics, such as its influence on visibility and aviation operations. By distinguishing fog from other meteorological phenomena, it becomes clear that the main factor defining fog is the presence of these tiny liquid droplets that significantly impact atmospheric conditions at ground level.