Overcast

Definition of Overcast

Overcast refers to a meteorological term denoting the state of the sky when clouds envelop the sky completely or nearly in entirety, generally at low or middle altitude. The consequence of an overcast sky often involves diminished sunlight penetration to the Earth's surface, engendering lower temperatures and a predominantly dreary appearance.

Types of Clouds Causing Overcast Conditions

Overcast conditions result from the contributions of several cloud types:
Stratus Clouds: These are gray, low-level, non-descript clouds that frequently span the entire sky, inducing uniformly overcast conditions.

Nimbostratus Clouds: These are dark, low-level clouds responsible for the generation of continuous, expansive precipitation, thereby cultivating an overcast and rainy ambiance.

Altostratus Clouds: These middle-level clouds engender a uniform, gray layer in the sky. They have the capacity to render the sun or moon as a vague, unclear disk, yet typically do not yield precipitation.

Impact of Overcast Conditions on Weather

Overcast skies have the potential to impose a variety of effects on local weather patterns:
Temperature: Overcast conditions can instigate cooler daytime temperatures due to the inhibition of sunlight reaching the Earth's surface. Conversely, at night, the cloud cover can perform a thermal insulation function, capturing heat and causing elevated temperatures.

Precipitation: Overcast skies, particularly those populated with nimbostratus clouds, have the potential to induce continuous, extensive rainfall or snowfall.

Visibility: Overcast conditions occasionally result in compromised visibility, particularly if paired with fog or precipitation.