How do tornadoes form?

The main reason of tornado formation is that cold and warm air masses collide with each other.

Tornado, that is, a sharply rotating funnel-shaped cloud column extending from cumulonimbus clouds. It is a vertical hollow rotating airflow between the bottom of cumulus and the underlying surface, and it is a disastrous weather phenomenon at local scale. Tornadoes can be found in tropical and temperate regions, including the interior of the United States, western Australia and northeastern India.

Tornadoes are seasonally weak, and can occur in spring, summer and autumn. It usually occurs at the turn of spring and summer or in the transitional season (April ~ 10) at the turn of summer and autumn, and the former is mostly. Tornadoes can be divided into multi-vortex tornadoes, land tornadoes, waterspouts and so on. According to their shape and production environment.

Tornadoes usually have a wind speed of 30 to130m per second, a diameter of less than 2km, an activity range of 0 to 25km and a duration of about10min. According to the enhanced Fujita scale (EF), the intensity of tornadoes can be divided into five grades. Sandstorms and fire cyclones are similar to tornadoes, but they are not tornadoes.

Tornado conditions include near-surface wind shear, vertical motion and energy instability. Thunderstorm is an ideal environment that can meet the above conditions, and it is also the main cause of tornado.

Among them, the tornado caused by supercell is called supercell tornado, and other cases are called non-supercell tornado. Supercell tornadoes account for 80% of the total number of tornadoes, and their intensity and development scale are usually larger than those of non-supercell tornadoes.

Tornado is a meteorological disaster. Modern weather forecast can warn tornadoes through high-frequency observation, but it requires high forecasting experience. In addition, some areas also carry out manual observation and data collection on tornadoes, that is, the "storm discovery" project.