根据美国国家气象局的资料，龙卷风是由雷雨云所形成，旋转速度每小时可高达600公里以上。

According to the U.S. National Weather Service, tornadoes form from thunderclouds and can reach swirling speeds in excess of 600 kilometers per hour.

你无处可走，只能沿路而上，你开始诅咒自己为什么没有选择一个更合适的时间开始攀登以避免这不可避免，在下午必然会出现的雷雨云帖。

With no place to go but up, you silently curse yourself for not getting a proper alpine start to avoid the inevitable afternoon thunderheads .