Thick, low-lying cloud near the surface of the earth is

called fog. Fog occurs when air near the surface becomes cooled to the dew point temperature, causing the water vapor in the air to condense into tiny water droplets. This condensation forms a cloud-like layer that reduces visibility and can create a misty or hazy atmosphere. Fog can occur in various locations, such as valleys, coastal areas, and during specific weather conditions like high humidity or temperature inversions.