What atmospheric condition is typically associated with reduced visibility and increases in humidity?

Fog is the atmospheric condition that is typically associated with reduced visibility and increases in humidity. It forms when water vapor in the air condenses into tiny water droplets that are suspended in the atmosphere, creating a thick mist. This process usually occurs when the air cools to its dew point, especially during the night or early morning when temperatures drop. The water droplets scatter light, leading to significantly reduced visibility, often below one kilometer.

In contrast, haze does not significantly increase humidity and is usually caused by larger particles in the air, such as dust or pollution, which reduces visibility but does not necessarily involve the same level of moisture as fog. Clear skies, on the other hand, are associated with low humidity and good visibility. Dew refers to moisture that condenses on surfaces during the cooling of the night, but it does not significantly affect air visibility in the same way fog does. Thus, fog is distinct for its capacity to combine high humidity with drastically reduced visibility.