Difference Between Fog and Mist, Visibility, Droplet Concentration

Visibility Range

Fog reduces horizontal visibility at the Earth’s surface to less than 1 kilometer. 

Mist reduces visibility but not below 1 kilometer. Objects remain visible at moderate distances.

Droplet Concentration

Fog contains a high number density of microscopic water droplets suspended close to the surface. 

Mist has fewer suspended droplets per unit volume of air. 

Droplet Size and Structure

In fog, droplets are large enough and numerous enough to be visible to the naked eye when illuminated. Their size distribution and turbulent movement contribute to rapid changes in fog thickness over short distances and time.

Mist droplets are generally smaller and more sparsely distributed. They are not easily visible individually, and their structure remains relatively uniform, producing a smoother and lighter haze near the surface.

Moisture Sensation

Air during foggy conditions feels damp, moist and sometimes wet. Surfaces often become coated with moisture due to continuous contact with dense droplets, leading to reduced comfort and increased surface wetness.

Misty air feels only slightly moist and rarely wet. The lower water content means surfaces usually remain dry or only mildly damp, causing minimal physical discomfort compared to fog.

Visual Appearance

Fog forms a thick whitish veil that blankets landscapes uniformly.

Mist appears as a thin greyish veil that lightly covers the landscape. 

Light Interaction

Fog strongly scatters and diffuses light due to dense droplets. 

Mist scatters light weakly, allowing better contrast and color perception.

Duration

Fog often persists for longer durations because of stable droplet structures and continuous moisture supply.

Mist is usually short lived and dissipates quickly with slight warming or air movement.

Spatial Extent

Fog can cover large continuous areas, especially in valleys, plains, or coastal regions. 

Mist generally occurs in localized patches and thinner layers.

Association with Pollution

When fog mixes with smoke or dust, it may take on faint coloration and enhance chemical interactions between droplets and pollutants. Such conditions can intensify atmospheric chemical reactions near the surface.

Mist has a weaker interaction with pollutants due to lower droplet density. Chemical reactions within droplets are limited and visual discoloration from mixed particles is generally minimal or absent.