Tuesday, 28 March 2017

Expect fewer cyclones, but the ones that form will pack a wallop

There was a point earlier this summer when Aussies in the Top End started to wonder: Where the hell are the cyclones?

The Australian region is usually hit with 11 cyclones each season - which runs from November 1 to April 30 - but only five tropical cyclones have been named in 2016-17. The 2015-16 season was the least active on record, with only three tropical cyclones declared.
In other words, it has been eerily still.

That was until today, when a Category 4 monster will hurtle towards the Whitsundays.
The region is expected to endure destructive winds, gales and a dangerous storm surge when the cyclone hits this morning.

The latest research into cyclones suggests that this will become the norm: fewer cyclones, but the ones that do form will be destructive.

That means stronger winds, more ferocious storms and heavier rain.

Cyclones need a very specific set of conditions in the atmosphere and ocean to form. Climate change has made those conditions harder to find, which is likely to lead to fewer tropical cyclones around the world, according to University of Melbourne cyclone expert Associate Professor Kevin Walsh.

One of the key conditions is sea-surface temperature above 26.5C and cool conditions in the upper part of the troposphere, which is found 15km above sea level.

"Climate change is causing the upper troposphere to heat up even more, and so the atmosphere becomes more stable," Dr Walsh told the university's Pursuit website.


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