The most important thing missing about your tornados is that it's not clearly tube or wedge shaped like a real tornado and unlike a real tornado yours is transparent. The tornado should also merge with the sky (unless you make it clear that that merged area is outside the canvas). Check some photo's of real tornado's as reference. Also do a search, because I remember that there was a tutorial on making a tornado once. Maybe Pidjy made it, but I'm not completely sure about that.

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