Weather Word Wednesday: Cap

Updated: Oct. 12, 2022 at 12:00 PM CDT
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QUAD CITIES, Iowa/Ill. (KWQC) - This week’s weather word is “cap,” and it can lead to a complicated forecast during the spring and summer months.

The cap is an important ingredient when forecasting whether or not severe weather will occur.

As the temperature warms up during the day, the air parcels near the ground begin to rise. This is known as an updraft.

As long as the temperature of the ambient environment is cooler than the parcel of air will continue rising and eventually lead to cloud development.

However, if the temperature warms with height and inversion is formed, stopping the air from rising and preventing the cloud from growing taller into an eventual thunderstorm.

The warm air aloft usually forms several thousand feet above the Earth’s surface.

In an uncapped environment, the air continues to rise as the environment cools with height, allowing the clouds to grow into thunderstorms.

If there is only a thin layer of warm air, making the cap weak, it can be broken which allows storms to form.

The longer the cap is in place, the more unstable the air below it gets. if the cap breaks, explosive thunderstorm development can occur.

Watch the video at the top of this page for an example of how the cap works, using a soda bottle.

Previous Weather Word Wednesday segments on Quad Cities Today at 11:


Heat Burst

Storm Surge