Wall cloud facts for kids

Wall clouds with lightning and rain

Wall clouds are special clouds that form under big thunderstorms. They look like a lowered part of the main storm cloud. Sometimes, they are also called "pedestal clouds" because they can look like a base for the storm.

Wall clouds are often seen with strong thunderstorms that might produce tornadoes. However, not all wall clouds lead to a tornado.

What are Wall Clouds?

Wall clouds are a type of cloud that drops down from the base of a thunderstorm. They form in an area of the storm where there is no rain falling yet. This area is often called the "rain-free base."

These clouds can be quite large and stay in one place for a while. They are a sign that the thunderstorm is very strong and organized.

How Do Wall Clouds Form?

Wall clouds form when warm, moist air gets pulled into the thunderstorm. This process is called "entrainment." Imagine the storm sucking in air from its surroundings.

Here's how it works:

• Warm, wet air from outside the storm flows into it.
• This air rises up into the storm.
• At the same time, cooler air that has been rained on starts to sink. This is called a "downdraft."
• When the warm, rising air meets the cool, sinking air, it creates a special area.
• In this area, the warm air cools down and forms the wall cloud. It's like a battle between warm and cool air, and the wall cloud forms where they meet.

Do Wall Clouds Always Rotate?

Some wall clouds spin around, and some do not. When a wall cloud is spinning, it means there is a strong rotating column of air inside the thunderstorm. This spinning column is called a "mesocyclone."

A mesocyclone is a key ingredient for a tornado to form. So, if you see a wall cloud that is rotating, it's a serious sign that a tornado could be developing. However, even if a wall cloud is rotating, it doesn't always mean a tornado will happen. Many rotating wall clouds do not produce tornadoes.

It's important to remember that a wall cloud itself is not a tornado. It's a cloud feature that can sometimes be a sign of a tornado.

Images for kids

• 

  A wall cloud with a tail cloud.

• 

  A shelf cloud over Enschede, Netherlands. (Note: A shelf cloud is different from a wall cloud.)

• 

  High-precipitation (HP) supercells.

• 

  A tornadic wall cloud with a RFD clear slot.