Tornadoes, it turns out, are about as American as apple pie. The United States is home to the majority of all the tornadoes that touch down around the world every year. Most of these twisters are small and only last a couple of minutes, but a small percentage of them can grow enormous and last for many hours, sometimes tearing a path across entire states. The largest tornadoes are in a category all their own as some of the scariest weather conditions nature can create.

1. HUGE TORNADOES REQUIRE HUGE THUNDERSTORMS.

The average tornado is only a few hundred feet wide, but some can be as narrow as a single vehicle or as wide as a mile or more across. The largest tornadoes require immense thunderstorms called supercells in order to form. A supercell is a thunderstorm with a rotating updraft. This rotating updraft helps the storm become strong and resilient. This extra boost gives supercells the ability to produce hail the size of baseballs or larger, intense winds, and enormous tornadoes.

2. THE HOOK BRINGS YOU BACK.

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Tornado supercell radar image
A radar image of the supercell that produced a mile-wide F5 tornado near Oklahoma City on May 3, 1999.
Image: Gibson Ridge

Tornadoes usually form in the “hook echo” of a supercell, which is the point where winds wrapping around the storm meet with the updraft racing skyward into the storm. This hook echo is ominously visible on radar imagery and a stunning sight in person. Scientists are still studying why some supercells produce tornadoes and others don’t, but a well-defined hook echo is usually a bad sign that things could get ugly in a hurry.

3. THEY CAN STAY ON THE GROUND FOR A LONG TIME.

Large tornadoes typically have long tracks. Many of these unusually wide storms can stay on the ground for dozens of miles, sometimes traversing several states before finally dissipating. A recent tornado in Wisconsin tracked along a path more than 80 miles long. Unfortunately, when a tornado covers so much ground, it’s more likely to hit populated areas. Many of the tragic tornadoes we’ve seen in recent history caused the amount of damage they did not just because they were intense, but because they covered so much land.

4. SIZE CAN BE DECEIVING.

You shouldn’t judge a tornado solely by its size. Some small tornadoes can produce scale-topping winds, while some big tornadoes are more bark than bite and leave only minor damage—to barns or farm equipment, for example—in their wake. A tornado itself is a rotating column of wind, and it’s the wind that matters. The reason we can see tornadoes is that the low pressure within that column condenses moisture in the air, producing a funnel cloud. If a tornado moves through an area with lots of dust or loose soil, it can make the storm look much larger than it actually is.

5. SOME BIG TORNADOES ARE MADE UP OF SMALLER TORNADOES.

A huge twister can be one terrifying wedge of darkness, but it’s more common for these storms to have several smaller vortices swirling within the larger tornado itself. Storm chasers report this as a "multiple-vortex tornado.” There is some truth to the saying that a tornado can demolish one house and leave the home next door untouched. Some of the worst and strangest damage seen after big tornadoes is attributable to the small, quick “suction vortices” that circulate within a large tornado, sort of like horses going around on a carousel.

6. THE CENTER OF A TORNADO CAN BE RELATIVELY CALM.

If you’ve ever seen the famous final scene of the movie Twister, you’ve probably wondered whether it really is calm and clear in the center of a tornado. It’s not exactly the eye of a hurricane, but the middle of a tornado usually is the calmest part of one of these storms. It’s extremely hard to record (or even see) the inside of a large tornado, but depending on how big it is, the relative lull is likely fleeting and probably still contains gusty winds and flying debris.

7. IMMENSE TORNADOES CAN DO HORRIFYING THINGS.

It’s unsettling to think about what 200-plus mph winds can do when they tear through a populated area. The EF-5 tornado that struck Joplin, Missouri, in 2011 was so strong that it warped and shifted the entire structure of a hospital, requiring its demolition. It’s common to hear reports of trenches scoured into the earth and pavement ripped out of the ground from the intense winds. And there are plenty of accounts of more unusual damage, too, such as thin pieces of wood being driven through a tree trunk or a plastic drinking straw allegedly cutting through a piece of sheet metal.

8. OKLAHOMA IS GROUND ZERO FOR THESE BEHEMOTHS.

The central United States is aptly nicknamed “Tornado Alley” for its tendency to see more tornadoes than anywhere else in the world, and that total includes at least a couple of big, mile-wide tornadoes every year. Central Oklahoma holds the record for both the largest and the strongest tornadoes ever recorded. A tornado that touched down in El Reno, Oklahoma, on May 31, 2013, measured 2.6 miles wide at one point, easily breaking the record for the widest tornado ever observed. Back in 1999, a mobile Doppler weather radar recorded winds of more than 300 mph in an F5 tornado that touched down south of Oklahoma City.