So the difference is that a gustnado doesn’t connect to a cloud.
For something to count as a tornado it has be to a vortex of air (a vortex means the air is spinning in a circle) that is tall enough that the top of that vortex reaches the clouds.
A gustnado *is* a vortex of air, but *not* one that is tall enough to be counted as a tornado.
This distinction is useful/important because without being tall a gustnado can’t last very long. A tornado can suck in more and more air and keep going, but since a gustnado can’t do that it will die pretty quickly.
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