Shelf Clouds: Basics Explained

Last week in Haridwar, Uttarakhand saw a massive shelf cloud which got captured in a viral video.

                       Shelf clouds, a meteorological phenomenon, form as cold air within the storm rushes out lifting warm moist air ahead of the storm. As that warm air lifts it condenses and a shelf cloud forms. What you will experience as a shelf cloud moves towards you is first heavy winds and then rain and hail

Shelf clouds are often associated with squall lines, and many times they are reported as wall clouds, funnel clouds, or rotation. A shelf cloud will usually be associated with a solid line of storms. The wind will come first with rain following behind it. It may appear to rotate on a horizontal axis.

These unique cloud formations often resemble a large, horizontal wedge or shelf extending from the base of a thunderstorm or cumulonimbus cloud. Shelf clouds typically form along the leading edge of thunderstorms, where moist, warm air is uplifted rapidly due to an advancing cold front. As the warm air is lifted, it cools and condenses, forming a cloud.

The advancing cold air creates a distinct boundary, known as the gust front or outflow boundary, which triggers the formation of the shelf cloud.



Clouds are aggregates of very small water droplets, ice crystals, or a
mixture of both, with its base above the earth’s surface. A classification is
made in level – high, medium, or low – at which the various cloud genera are usually encountered.   In temperate regions the approximate limits
are high, (16500 – 45000 ft); medium, 2­7 km (6500 –23000 ft); low, 0­2 km (0 –
6500 ft).

The high clouds are Cirrus (Ci), Cirrocumulus (Cc),Cirrostratus (Cs).

The medium clouds are Altocumulus (Ac), Altostratus (Asthe latter often extending higher) and Nimbostratus (Ns) (usually extending both higher and lower);

The low clouds are Stratocumulus (Sc), Stratus (St), Cumulus (Cu), and Cumulonimbus (Cb).

Low, thick clouds primarily reflect solar radiation and cool the surface of the Earth. High, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by
the Earth
and radiate it back downward, thereby warming the surface of
the Earth.



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