Shelf Clouds

Shelf Clouds

News: Shelf clouds were in news recently because a video claiming to show a shelf cloud formation in Haridwar,
Uttarakhand, has gone viral on social media.

What are shelf clouds?
• A shelf cloud is a type of arcus cloud, characterized by its impressive and intimidating appearance. It is a low, horizontal, wedge-shaped cloud that is attached to the base of the parent cloud, which is usually a thunderstorm cumulonimbus, but could form on any type of convective cloud.

When do shelf clouds form?
• Shelf clouds form when cold and dense air is pushed by the wind into a warmer air mass. The rush of cold air often occurs in a thunderstorm’s downdraft, when the cold air rushes towards the ground and spreads out to create a gust front. As the cold air lifts the warm air, water vapour condenses into cloud droplets and forms the shelf cloud.
• Shelf clouds are often associated with powerful storm systems, and many times they are reported as wall clouds, funnel clouds, or rotation. However, shelf clouds usually do not cause tornadoes or extremely dangerous weather on their own. They often appear ahead of powerful thunderstorms with heavy rain, strong winds, and occasionally hail or tornadoes.