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Dear Tom,
You recently mentioned that thunderstorm clouds can rise 10 to 12 miles into the atmosphere. Can you elaborate?
— John Sunderman, Downers Grove

Dear John,

Cumulonimbus or thunderstorm clouds are the tallest clouds on this planet, and the general rule of thumb is the higher the top, the more severe the storm is likely to be.

Thunderstorms with the greatest vertical build host the strongest updrafts, sometimes as high as 100 mph, that can propel the cloud tops to great heights. In the Chicago area, typical summer thunderstorms cluster in the 35,000-45,000 foot height range, while tops of severe thunderstorms can grow to 60,000 feet.

The parent cloud of the devastating F-5 Plainfield tornado (29 fatalities) on August 28, 1990, towered to 65,000 feet. Thunderstorm tops in the tropics have been measured to 75,000 feet — more than 14 miles high.

Cumulonimbus or thunderstorm clouds are the tallest clouds on this this planet, and the general rule of thumb is, the higher the top, the more severe the storm is likely to be.