Seeing a funnel cloud on the horizon is one of the scariest things anyone can witness. But not all tornadoes are created alike.
Great differences in how they form, along with their size and shape, correspond with tornadoes’ varying potential for destruction.
Here are some types of tornadoes – and other, much smaller phenomena that spin up like tornadoes – and how to tell them apart.
Supercell tornadoes
Wedges are generally the biggest and most destructive twisters. They’re pretty easy to spot because they’re usually as wide as they are tall.
Wedges come from supercell thunderstorm systems, which also produce similar twisters known as stovepipes, ropes, elephant trunks or multi-vortex tornadoes.
“It’s almost always an indication that the tornado is very strong and would likely rate on the higher end of the enhanced Fujita scale. EF-3, -4 or -5,” said CNN senior meteorologist Brandon Miller, who is also a storm chaser.
“It’s not always the case,” he said, “but a good majority of the time, wedge tornadoes are your biggest, largest and most destructive of the tornadoes.”
These are the monsters that can be half a mile wide or bigger. The widest tornado on record in the United States is the wedge twister that hit in 2013 near El Reno, Oklahoma. It was 2.6 miles wide, with winds close to 300 miles per hour and stayed on the ground for 40 minutes. It killed eight people, including a trio of storm chasers.
Non-supercell tornadoes
These are often recognized as landspouts and waterspouts, and the weather doesn’t have to be horrible for them to form.
They are skinnier, sometimes rope-like, and don’t last as long as their wedge tornado cousins, so they tend to be more localized and do less harm.
“It’s not going to do much, if any, damage,” Miller said. “It’s very localized, and it’s not going to go very far.”
They can pop up even when it’s cloudy and during periods of light rain, if wind conditions are right on land or over a body of water.
“Again, these are not terribly dangerous,” he said.
Tornado-like vortices
Let’s begin with gustnadoes – and no, that’s not a made-up word. These are “just little spin-ups” that pop up along what’s called the gust front of a storm system, Miller said.
They’re not technically tornadoes, but they spin stuff around a vortex, so they look like the real thing.
Similar are dust devils, which are those little whirlwinds that whip up dirt on baseball infields and trash at the exterior corners of buildings. They happen all around us all the time, he said, but we don’t notice them unless they pick up some dust (thus their name) or other debris, like leaves.
“Dust devils can form in perfectly sunny skies,” Miller said. “You just get heat that warms one place a lot, and you can get some spin to the winds just because of the difference in heating.”
Heat also plays into the formation of fire whirls. Bits of super-heated air from fires start to spin, then rotate flames inside a vortex. These are – you guessed it – fire tornadoes.
One particular fire whirl, during the devastating Carr Fire in 2018 in Northern California, turned into an EF-3 tornado, Miller said, and grew to a half mile wide.
“That had never really been seen to that scale before,” Miller said. “Things like fires that are incredibly hot can have their own weather associated with them and have their own whirls.”
This fire whirl, which developed near Redding, reached speeds of 143 mph.