system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: if tornadoes occur nearly everywhere on Earth, why is it that the US has all the largest and most devastating ones?

Why aren't they as large in say Europe or Australia? Or anywhere else really.
gpt
Topography and location. 

The US has a large flat area where cold air from the north can battle hot humid air from the south. These conditions create storms, and sometimes potent tornadoes. 

The Arctic is a stones throw north of tornado alley, whereas the humid warm Gulf of Mexico is just south. As a result, they tend to collide, producing seriously potent storms. 

Europe and other places don’t have this setup. There’s no gulf to provide highly humid and warm fronts in Europe, at least not where cold arctic fronts will collide with it. Mountains and landforms impede this exchange, which Europe has in abundance. Australia lacks the climate transition, and has strong topography to further restrict the issue.