美国，为什么那么多龙卷风？

Tornadoes are twisting, fierce winds. 龙卷风是会打转的凶猛大风。 Cold air rushes in from the north. 冷空气从北方冲过来。 Warm wet air rushes up from the south. 暖湿空气从南方升上去。 They crash into each other on the flat plains. 它们在平坦的中部平原相撞。 A twisting column is born. 一个旋转的风柱就这样诞生。 That is why the US has so many tornadoes. 所以美国的龙卷风特别多。