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Come spring, when the dark clouds hover over the United States, people can sense the coming of a tornado. What have been of much worry to the scientists is that what causes these twisters, though they make some assumptions that the atmospheric conditions, altitude and supercell (intense thunderstorm which rotates violently in an upward motion) thunderstorms swell up into the sky to form a tunnel of deadly and violent air.

Researchers are of late assuming that the heavy rains accompanied with supercell thunderstorms can be the leading cause for the ensuing of tornadoes. Robert Davies-Jones from the National Severe Storms Laboratory, Oklahoma is of the opinion that heavy rains accompanies with violent supercell thunderstorms can push the air updraft to form a tunnel of violent, gushing air that rotates vigorously and can be identified as a twister.

Robert also opines that a severe storm does not require rains but a tornado is always followed by heavy rains and acute thunderstorms. This simple fact was discovered as early as in 1953 when scientists through a radar peered into the supercells to find that in tornadoes, the rains were caught up in a hook which they named the “hook echo”. Infact, it became a tell-tale radar marker for an ensuing tornado.

Though at that time the “hook echo” was only regarded as a by-product of a tornado, Robert Davies-Jones believes it to be the other way round. According to him, the hook echo is not a passive but an active mechanism by which a tornado really forms.

Jones observed how falling rain would kick-start the upward circulation of air that led to a lethal tornado. He also observed as to how the falling rain also got twisted along with the twisting gush of air and debris, finally passing on its energy to the updrafting air just at the side of it.

It was further revealed through the studies that rain acts like a sheet around the swirling winds with the air inside the rains stretching out as the funnel moves up to touch the skies, thereby increasing the speed and intensity of the storm which gives rise to a tornado.

David Lewellen from the University of West Virginia is of the opinion that further studies and reports are required to confirm whether rains have a hand in the formation of killer tornadoes. He feels that rain is just another weather condition that is just right or appropriate for a tornado to form. David opines that other field campaign experiments which are to follow in the spring months of 2009 and 2010 will hopefully establish what has been presumed – that heavy rains cause tornadoes.

Davies-Jones works’ are published in the August issue of the Journal of Atmospheric Sciences.

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The Smoke signals have become very obvious and they are a signal to suggest that something more serious is about to happen. The volcano on the island of Montserrat discharged a eight-kilometer-high cloud filled with very hot ash and gas. The amount of ash is so much that it could possibly lead to a disastrous eruption.

“I think it was a warning call … of what it can do,” Vicky Hards, director of the Montserrat Volcano Observatory, told the Associated Press.

The residents have every reason to be scared of the Soufriere Hills volcano, as in 1997 it wiped out the tiny Caribbean island’s evacuated capital, Plymouth, which killed around 19 people and killing around half the island’s population of around 10,000.

Every week the crater’s lava dome is continuing to grow, and this process has began since december 24. Because the eruption failed to cause the lava shell to collapse, experts are worried that the mounting pressure could be released in a much more powerful blast.

Such an eruption could be very lethal and send hot ash and gas down the northwestern flanks of the mountain. As a result, the government of U.K. asked families living around these areas to evacuate.