Why is Hurricane Sandy So Damn Big?
By on October 30th, 2012

Sandy is big! And it’s hitting the east coast of America with a vengeance. The adjectives being thrown around are ‘superstorm’, ‘Frankenstorm’ and ‘The perfect storm’. And the bad news is that all of these adjectives seem apt. Sandy is moving in fast from the east coast, boasting a fiery looking ‘eye’, which is nearly 150 km in diameter. The whole storm is somewhat close to 700 km. Worsening the situation is a cold front that is moving in from the north to the south, independently of Sandy’s activities. The fearful collision is awaited.

Hurricane Sandy as it makes landfall over Cuba.This is taken in infra-red. (Photo Courtesy: NOAA/NASA)

Sandy has forced the evacuation of reportedly 3.5 million people in New York alone. Sandy has been upgraded from a tropical storm to an extra-tropical storm. While this classification can be made just from the location of the storm – tropical storms occur in the tropics and extra-tropical ones out of the tropical regions – the correlation with storm size is direct. Extra-tropical storms always tend to be larger than tropical storms. Sandy has just moved northwards and has become even bigger.

Cyclones

Cyclones are one of Nature’s ways of transferring heat from the tropics to the polar regions. This happens only when the transfer needs to be dramatic – i.e. when the heat difference built up is large. There are other less destructive ways of heat transfer, including air currents like the jet stream, ocean currents like the Gulf Stream current and, of course, the prevalent winds. Cyclones are natural consequences of heat build-up in one region of the ocean. This creates a local low-pressure region. Colder winds from the surroundings rush in, but this chaos makes the wind swirl around the central ‘eye’. If the heat difference is large, the ocean’s heat can fuel the process to massive proportions.

The cyclone will move away from the equator, because that’s what wind systems do – move from hotter regions to colder ones. Plus, the rotation of the Earth makes sure that worldwide cyclones hit just the east coasts of landmasses! (Check this fact out and try to find an exception).

Worse…

Now that Sandy is moving further north, it will weaken because the ocean waters get colder and thus the heat source is no longer as proactive. But wait! The Gulf Stream – a warm ocean current moving along the east coast of N. America – is actually acting as a substitute for the ocean warmth. Since it carries warm water and flows along the surface of the ocean, it is intensifying Hurricane Sandy! Bad bad news! Sandy is expected to follow the warm water trail along the east coast, before it is driven on land.

A newer surprise is awaited when Sandy meets a cold wave that is coming in from the north. But that’s for another time.
Stay safe everyone and heed the warnings by the authorities.

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Author: Debjyoti Bardhan Google Profile for Debjyoti Bardhan
Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.

Debjyoti Bardhan has written and can be contacted at debjyoti@techie-buzz.com.

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