I read once about how a tornado picked up a semi, and it remained in the vortex a lot longer than I would have anticipated, especially since I figured it would have flung tangentially, but something kept it in the vortex. What is that “something”?
I read once about how a tornado picked up a semi, and it remained in the vortex a lot longer than I would have anticipated, especially since I figured it would have flung tangentially, but something kept it in the vortex. What is that “something”?
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not a tornado scientist my layman assumption is that the air is moving faster the further away from the centre of the tornado, and that faster air effectively pushes debris around the circle rather than letting it project outwards.
Or at least something to do with differing wind speed at different points in the cross section?
Low air pressure “sucks” things into the center like a vacuum cleaner. How much an object is affected depends on the surface area, while body forces like gravity and centrifugal force depend on the mass of that object. In simple words: Large light objects fly into the tornado, while small heavy objects are ejected outwards.
PS: I have no idea what a semi is.
PPS: I just came up with this explanation, no idea how accurate it actually is. I know that pressure in vortex center is low though, the rest just seems reasonable to me.
A big thing is that there is low pressure in a tornado that tends to pull things inward. At low levels, air spirals into the tornado and then upward. Wind in a tornado is also far from a simple spiral movement and is quite turbulent. Many tornadoes have even smaller vortices inside of them, which further complicates how debris moves inside of them.
An empty semi trailer is also relatively light for its size, so it would be less likely to be flung outward than something more compact.
There’s a very low pressure zone at the center which is fairly effective at keeping things inside. There’s also cold air going down and warm air going up which causes the twisting of air so in practice it’s more like the truck is being pulled straight up by the low pressure zone and the vortex is usually for lighter objects and air. But depending on the tornado it COULD also totally launch that truck. Tornados are shockingly unpredictable and random even within a single storm and objects being picked up can be shredded, launched out, or set down completely unharmed.
The “tornado,” that we see isn’t the actual thing that’s causing the forces and stuff. What’s actually causing the forces is a mixture of hot and cold air pushing each-other around, causing things from around the tornado to get sucked into the funnel.
Have you ever drained a tub or something and noticed the cyclone/water-tornado around the drain? That’s basically what a tornado actually is, where air is getting sucked in from all around, all we see is just the narrow center bit where all the dust collects.
A tornado is formed when warm air rises creating a low pressure area. The surrounding air rushes in to take its place. All that surrounding air has some angular momentum and when it gets pulled toward the center, it gets faster like a figure skater pulling their arms in.
So all the air is moving in and up, and rotating as it does so. So if the wind is strong enough to pick something up, it’s going to pull it in. To be flung out like you are thinking, the centrifugal force would have to be stronger than the centripetal force, but the same wind is providing both.