10 Things You Didn't Know about Tornadoes
Ever wonder why they’re more frequent in spring? And how fast they actually blow? We have the answers.
To meteorologists, a tornado is a violently rotating column of air, which is connected to a cumuliform cloud at one end and the ground at the other. They're usually visible as a funnel. To the rest of us, they're just frightening. Now that it's April, we're at the beginning of the season in which tornadoes appear most frequently, which starts first in the Southeast and gradually spreads westward and northward. ￼ Scientists still can't completely explain why tornadoes form. The classic explanation is that warm, moist air from the Gulf of Mexico meets cold Canadian air and dry air from the Rockies. But as the National Oceanic and Atmospheric Administration's tornado FAQ notes, most thunderstorms that form under those conditions don't form tornadoes. We do know that the most destructive and deadly tornadoes occur from supercells -- which are rotating thunderstorms with a well-defined radar circulation called a mesocyclone. Here are some surprising and intriguing facts about the fearsome funnels.
Tornadoes can abruptly change direction, or even backtrack, when they're hit by outflow winds from a thunderstorm's core. But most move in the same directions -- from southwest to northeast, or west to east.
Tornadoes come in different colors. Some are white, while others are black or gray, or even red. They tend to look darkest when you're looking at them toward the northeast in the afternoon, when they're silhouetted in front of a light source such as brighter skies west of the thunderstorm.
The United States had 1,259 tornadoes last year, according to NOAA. Texas had the most, with 228, followed by Kansas with 178. Here's a 2007 tornado from Texas.
The deadliest tornado in history was the infamous Tri-State Tornado that occurred on March 18, 1925 and hit Missouri, Illinois and Indiana, causing 695 fatalities.
The most tornado-prone city in America is Oklahoma City, which has been hit by more than 100 over the years. Here's an image of a 2009 tornado that hit the city.
The biggest tornado in history was the Hallam, Neb., tornado of May 22, 2004, which had a peak width of nearly 2.5 miles. Above, the wreckage it left behind.
The tornado with the fastest wind-speed ever recorded occurred near Bridge Creek, Okla. on May 3, 1999. It was measured at 302 miles per hour.
There's a popular misconception that tornadoes can't pass over valleys, mountains, lakes or rivers. When they pass over water, they become waterspouts.
Tornadoes occasionally merge. What usually happens is that a bigger, stronger tornado draws in and absorbs a smaller funnel, then keeps on going.