Tornadoes form from the ground up

The El Reno tornado, USA

A significant finding for countries that experience tornadoes …

For decades, the theory has been that tornadoes form high in the atmosphere (hundreds to thousands of meters high) and then later touch down on the Earth’s surface. Many of us have seen funnel clouds form in the sky and then stretch down toward Earth in the familiar narrow twisting shape of the tornado.

Now, surprising research based on tornadoes that occurred in Oklahoma and Kansas, USA, suggests that the tornadoes’ “swirling winds first develop near the ground.”

The research “compared radar measurements that tracked wind speed” with photographs and videos of tornadoes taken by storm chasers. The tornadoes’ “funnel was already on the ground several minutes before the radar data–taken roughly 250 meters off the ground–recorded any rotation.”

In addition, radar measurements taken nearer the ground “found rapid rotation … before it appeared higher up.” That pattern has been confirmed in multiple tornadoes.

This research has important “implications for how weather forecasters issue tornado warnings.” If tornadoes actually form first at ground level, weather warnings based on readings taken higher up may be slow “in sounding the alarm for tornado-strength winds.”

Read the article (Katherine Kornei, Science, December 13, 2018).

For more information about weather, search the Science Primary Literature Database and the Headline Science Database.

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