| 龙卷风 | tornado A rapidly rotating column of air developed around a very intense low-pressure centre. It is associated with a dark funnel-shaped cloud and with extremely violent winds (>300km/h) blowing in a counterclockwise spiral, but accompanied by violent downdraughts. The precise mechanisms are not fully understood but the following atmospheric conditions appear to be necessary for tornado development: a layer of warm moist air at low altitude; a layer of dry air at higher altitude with an inversion of temperature at about 1.000 m; a triggering mechanism, usually in the form of an active, intense cold front or solar heating of the ground which will create a vortex (空气柱围绕一个非常强烈的低气压中心快速旋转。它伴随着一个黑色的漏斗状云和极其暴力的逆时针螺旋吹的风(>三百公里每小时)，但其伴随的暴力倒陷，确切机制尚未完全了解，但以下的大气条件似乎是为发展所需的龙卷风：在低海拔温暖潮湿的空气层；在海拔较高的层与逆温层约1000米的干燥空气；通过某种触发机制触发，通常形式猛烈，强烈的冷锋或地面将创建一个漩涡太阳能加热过程。) |
