A shelf cloud is a horizontal wedge-shaped cloud which hangs low in the air, and is usually associated with severe weather.
It is a low, horizontal cloud that appears to be “shelved” out from the base of a thunderstorm.
The cloud is usually dark and ominous-looking, and often appears to be advancing rapidly towards the observer.
The rising cloud motion looks severe as it rises but it is the lower cloud that appears turbulent and wind torn.
The leading edge of a Shelf Cloud is known as the gust front.
When the warm air is drawn into the storm’s updraft and it mixes with the cooler air, the moist air condenses, and this creates a rolling effect people see and which usually develops into a heavy rainstorm.
A shelf cloud is also known as a “Tsunami” cloud due to what looks like a rotating motion as the cloud draws nearer to the land.
What causes a Shelf Cloud?
Shelf clouds are formed when cold air from the leading edge of a thunderstorm pushes out and under warm, moist air in the lower atmosphere.
This causes the warm air to be lifted and cooled, forming a cloud. The cloud can then become a shelf cloud as the leading edge of the thunderstorm moves closer to the ground.
Shelf clouds can often be accompanied by strong winds, heavy rain, and even hail.
While they are not necessarily a sign of a tornado, they can indicate the presence of a severe thunderstorm, so it’s important to take shelter if you see one approaching.
How often do Shelf Clouds occur?
Shelf clouds are relatively common, especially during the summer months when thunderstorms are most prevalent. They can occur in many different parts of the world and are not limited to any specific region.
Shelf clouds are most often seen ahead of a line of thunderstorms, and are a good indicator of approaching severe weather.
Overall, shelf clouds are a relatively common weather phenomenon and can be seen by anyone who is paying attention to the clouds and weather conditions around them.
If you are interested in observing shelf clouds, it’s a good idea to pay attention to the weather forecast and to be on the lookout for any signs of approaching thunderstorms.
Feature Image of a shelf cloud over St. Augustine Beach in Florida by Jody Hamilton and shared with The Weather Channel Facebook page.