Tornado怎么形成的？
A tornado is a vortex，And it was a violent vortex in the air。The air rotates rapidly around the axis of the tornado，Attracted by the decrease in the air pressure of the tornado，Within a thin layer of air several dozen meters thick near the ground，The airflow is drawn into the bottom of the vortex from all directions。And it immediately turns into an upward vortex around the axis，The wind in a tornado is always cyclonic，Its air pressure can be ten percent lower than the surrounding air pressure.

Tornado的形成
Tornado是云层中雷暴的产物。It occurs in the development of intense thunderstorm clouds，The temperature difference between the top and bottom is huge：The ground temperature is around twenty degrees Celsius；Under the thunderstorm clouds，The temperature dropped to around ten degrees，At an altitude of four thousand meters，The temperature drops0℃，And at an altitude of eight thousand meters，The temperature dropped to minus thirty or so degrees。In this way, the cold air descends，The hot air rose violently，Form many small vortices．Before these small vortices have developed，They often rise to the bottom of the clouds in groups of three or five，When extended, it is contracted to rotate and roll。A large vortex is formed only when the up-and-down turbulence is extremely intense——Tornado．Tornadoes usually occur in summer，And it came along with the development of a strong thunderstorm cloud。
Specifically speaking，A tornado is a form in which a small portion of the huge energy of a thunderstorm is concentrated and released in a very small area。The formation of a tornado can be divided into four stages：
（1）The instability of the atmosphere generates strong upward air currents，Due to the influence of the large transit airflow in the jet stream，It has been further strengthened。

（2）Due to the interaction with the wind that has shear in both speed and direction in the vertical direction，The updraft begins to rotate in the middle of the troposphere，Form mesoscale cyclones。

（3）As mesoscale cyclones develop towards the surface and extend upward，It itself becomes thinner and stronger。Meanwhile，A small-scale enhanced combination，That is, the nascent tornado forms inside the cyclone，The same process of generating a cyclone，Form the core of the tornado。

（4）The rotation in the core of a tornado is different from that in a cyclone，Its strength is sufficient to make the tornado stretch all the way to the ground。When the developing vortex reaches ground height，The ground air pressure dropped sharply，The ground wind speed rose sharply，Form a tornado。