Such is the nature of a tornado that an accurate prediction is almost impossible. A violent whirling wind-storm, affecting a narrow strip of country, the tornado is the most violent and destructive of all storms.

The word tornado is derived from the Spanish tornado which means a thunderstorm and altered to tornada which means turning. Technically speaking, tornadoes are local storms of short duration, formed of winds rotating at very high speeds usually in an anti-clockwise direction. A tornado is born in a thunderstorm. The chances of a thunderstorm being transformed into a tornado are very rare, indeed. In fact, as the weathermen informed us, about one in a few thousand. The tornado becomes visible as an all-consuming vortex, a whirlpool structure, of winds “rotating about half-cavity in which centrifugal forces create a hollow vacuum.” These storms occur over land and water alike and may pass from one to another without much change in force or appearance.

The formation of a tornado is due to a combination of the thermal and mechanical forces in the system. The destruction caused by it is also due to a combined action, this time between the high-speed rotary winds and the partical vacuum in the center of the vortex. Any ill-fated object in its devastating path becomes the victim of the enormous pressure difference and things are sucked in mercilessly and indiscriminately by the hungry and seemingly insatiable storm. As more and more debris is sucked up, the colour of the funnel becomes darker and more ominous.

The most exasperating thing for the weathermen is the loose usage of the terms ‘tornado’ and ‘cyclone’. As Prof. Y.P. Rao, Director-General (Observatories) at New Delhi was quick to point out, the two are at different ends of the spectrum. What usually occur in North and North-East Indian during the months March to June are not tornadoes but ‘squalls’. These are caused by the descent of cold air from a thunderstorm. The denser air descends with tremendous force and starts blowing with a high speed. Squalls are frequent, tornadoes in India are a rarity. Not more than one such occurrence is reported throughout the country in a year.

A tornado usually has a diameter of less than one kilometer while the cyclone has a diameter of at least a 100 kilometers. The tornado is short-lived, usually lasting for a few ferocious minutes. The rare record of a long-lasting tornado is one of seven hours and twenty minutes in the USA. The cyclone, on the other hand, lasts for at least 24 hours and usually for five to six days. The weathermen cannot be blamed if they storm angrily when such diverse terms are bandied about indiscriminately by laymen.

Most tornadoes that have occurred in India have struck in the rural areas and the one in Delhi was probably the first to hit a thickly-populated area. The last major reported tornado was near Ludhiana in 1975. The exact location was a village situated a few miles from the Punjab town. That it was a tornado was inferred from a bullock cart which was lifted up and thrown several feet. The death toll amounted to ten. The reason for the comparatively low number of deaths lies in the absence of concrete structures. And it is this occurrence in remote rural areas which makes reporting and recording of such storms difficult.

In 1963, a tornado swept the Cooch-Behar area. Its path lay through 33 villages; it left behind 139 dead, and 3,760 families were rendered homeless. Mr. R.K. Saxena of the Met Office went back over the years and talked about the 1838 tornado in the 24 Parganas. He seemed rather skeptical about the report that in that tornado, hailstorms of 1.6 kg each were seen. The tornado is a common occurrence in the USA. During the period 1953-69, that country reports an average annual occurrence of 642 tornadoes. And the average death toll since the year 1952 has been 120 per year. Tornadoes hit hard and often in the States and they usually occur in ‘families’ of two or three, Baldwyin in Mississippi was struck by two tornadoes within a space of 25 minutes in 1942. Oklahoma City has been hit 26 times since 1892. Minnesotta saw a strange sight in 1931 when an 83 ton railroad coach with its 117 passengers was lifted 80 feet into the air and thrown into a ditch. On one fateful day, April 11, 1965, thirty-seven tornadoes struck the Midwest and left behind 271 dead and 5,000 injured. And so the awe-inspiring figures trail on, mere records of unexpected destruction.

But, one might well ask, why these tornadoes cannot be predicted? The reason lies in the fact that no one can yet say when a thunderstorm will turn into a tornado. The only prediction which can be made with any certainty, is that of a severe thunderstorm. Even in the USA, only a tentative area with a high potential of tornado generation can be marked off. This area is usually 100 miles in width and 2590 miles in length. In India, where the occurrence is so extremely, rare, prediction becomes even more difficult. Research is on in the West to make more accurate and more localized predictions.

And with this lack of prediction, organized precautions become somewhat meaningless. The USA has a unique method of warning people. The national Weather Service is aided by 500 local Skywarn stations. These stations have trained tornado-watchers.

The warning comes only after the tornado has actually been sighted, either by these watchers or by radar. And even in places where there are no Skywarn stations, the people in tornado-prone areas are so used to these occurrences that the entire community keeps watch and issues warnings. The peculiar, localized nature of the destruction ensures that the community unites for purposes of warning, evacuation and shelter. Hence, it is the frequency of occurrence in the UA that has established a more efficient warning system. In India, the rarity of a tornado adds to its danger.

The unpredictability, vicious nature and the localized devastation make the tornado a ferocious fury of nature. Their time on Earth is short and their destructive paths are small. But the march of these short-lived, local storms through populated areas leaves a path of havoc and destruction. In seconds, a tornado can transform a thriving street into ruin and turn hope into despair; for of all the winds that sweep this planet’s surface, the tornado is perhaps the most violent.