Definition of Overcast
Overcast, a term originated from meteorology, describes the scenario when the sky is entirely or nearly fully covered by clouds, predominantly at a low to middle elevation. The resultant decrease in sunlight that reaches the Earth's surface often induces a reduction in temperature and a generally somber visual atmosphere.
Types of Clouds Causing Overcast Conditions
There are numerous cloud types that induce overcast conditions:
Stratus Clouds: Belonging to this category are low-lying, featureless, gray clouds that have the propensity to occupy the entire sky, causing a uniform overcast condition.
Nimbostratus Clouds: These are characterized as dark clouds residing at a low elevation, generating consistent, extensive precipitation, thereby setting a predominantly overcast and rainy environment.
Altostratus Clouds: Clouds of this type exist at a middle altitude and form a uniform, gray layer encompassing the sky. Their presence may cause the sun or moon to emerge as an indistinct, blurred disk, albeit precipitation is typically not a resultant factor.
Impact of Overcast Conditions on Weather
The presence of overcast skies may engender a range of impacts on local weather conditions:
Temperature: Overcast skies can cause a reduction in daytime temperatures due to the limited sunlight penetration to the Earth's surface. However, during nighttime, the cloud cover may retain heat, functioning akin to thermal insulation, thereby causing an increase in temperature.
Precipitation: Overcast skies, particularly those dominated by nimbostratus clouds, can generate persistent, widespread precipitation, taking the form of rain or snow.
Visibility: Overcast conditions may at times result in diminished visibility, especially when accompanied by fog or precipitation.