Posts Tagged ‘cyclones’

Possible twin cyclones off Aust coast 1:28

Possible twin cyclones off Aust coast 1:28
Three weeks after Cyclone Marcia and Cyclone Lan, a cyclone is expected to form off Queensland in coming days. The Bureau of Meteorology also says there is a high chance of another system developing off the coast of Western Australia by Wednesday.
Read more on The Australian (blog)

Powerful cyclone forms in Pacific
A large tropical cyclone named Pam has formed in open South Pacific waters north of Vanuatu and Fiji. The cyclone is expected to head south towards New Zealand and then curve to the east. Fiji's Tropical Cyclone Centre issued cyclone warnings early on …
Read more on The Dominion Post

Severe WA cyclone looms: BOM warns of low forming in the Indian Ocean
Bureau of Meteorology Perth duty forecaster Catherine Schelfhout says the Indian Ocean low is likely to reach cyclone strength by Thursday or Friday and later hit WA as a severe cyclone. "The timing is a bit variable but the conditions are very favourable.
Read more on WA today

Why is sea-surface temperature a critical factor in the development of tropical cyclones?

Question by Questions: Why is sea-surface temperature a critical factor in the development of tropical cyclones?
a) Why is sea-surface temperature a critical factor in the development of tropical cyclones?

b) Suppose that efforts to modify hurricanes are successful. Speculate on what this might mean for poleward heat transport.

Please give a detailed response for each question, thanks!

Best answer:

Answer by Michel Verheughe
Well, I read that the hurricane season in the southern part of the North Atlantic starts when the surface sea temperature reaches 27 degrees Celsius.

But what creates the energy needed to get the air moving at a speed corresponding hurricane force in the Beaufort scale?

Heat? No, difference of heat! It’s the principle of the chimney.

So, in order to form hurricane, you need a lot of moist and mild air under and … cold air above.

It is similar to global warming: Many predict terrible storms. Perhaps but not for the low pressures on the polar front. Because what makes the intensity of the storms there, is the fact that in the autumn and winter the north pole is very cold and the >>difference<< of temperature with the equator is much greater. But the global warming shows an increase of the average temperature over the arctic, a slight increase over the antarctic and none over the equator. Therefore the difference between arctic polar air masses and temperate ones should be less, right? Say, if the Coriolis effect didn't create a clockwise current in the North Atlantic, the sea between the Cape Verde islands and the Caribbean wouldn't be so warm and hurricanes wouldn't happen as it is for the west coast of the US that is in the cold Pacific current. But then, that is assuming that the air aloft is the same temperature as it is now. But if we change the climate, everything change, right? What about the temperature of the air at the tropopause? Talking about global warming we consider only the temperature at sea level and we don't really know how it affects the top of the troposphere. This is the point made by the environmentalists: we know what we have. It may not be the best but nature adapted to it. We don't know how climatic changes will affect us and that, in itself, is scary, isn't it?

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