Just as small objects in tornadoes tumble around and fall out of the vortex, you have to imagine that the sharks continually fall down as wind speeds decrease and change direction, but they may then be lifted back up again into the vortex as winds increase. So as the shark-ridden waterspout approaches land and becomes a sharknado, these sharks may fall from the sky onto unsuspecting humans. But how would they behave upon falling out of the sharknado? Would you really get a bunch of bloodthirsty beasts waiting to feast upon humans? Probably not.
Let's assume that the sharks are not at all harmed by being out of the water, getting tumbled around within the vortex, or being subjected to the pressure changes within the cyclone. Would the sharks want to eat people immediately upon falling out of the storm? Likely, no. Yes, they'd probably be agitated, but sharks don't generally like to eat people. Scientists speculate that sharks aren't very interested in humans, and usually only attack them when curious or because they mistake them for other sea creatures that are normally their prey – like seals [source: National Ocean Service].
But all those assumptions we just made about the sharks being alive upon falling out of the sharknado are completely out there. Sharks aren't able to breathe out of the water, as they need a constant flow of water over their gills to get oxygen. The waterspout may draw up some water droplets into it as it moves over the ocean, but it couldn't possibly draw up nearly enough water to keep the sharks happy and alive. Word on the fishing boats and docks is that sharks can still bite after they've stopped breathing, but involuntarily shutting their jaws on someone's hand is very different than a bloodthirsty attack.
So there we have it. We've painted a somewhat feasible picture of how a sharknado would form if it could, but it falls apart right at the end there with the on-land feeding frenzy. But have no fear: Even if a sharknado can't happen in real life, it will live on in Hollywood as they continue filming sequels.