OK, first a refresher on
how hurricanes form:
Hot air from
northern Africa is swept out over the Atlantic Ocean by the easterly (they blow
from the east) trade winds. It sucks up warm (typically over 85 F) ocean
water. The water is carried upwards until it condenses in the upper
atmosphere and releases the energy that it used to evaporate in the first
place. The released energy warms the air and it rises more, pulling up
more water, which condenses and releases energy, which warms the air ....
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| From UCAR - https://eo.ucar.edu/kids/dangerwx/hurricane3.htm |
Then the trade winds
push the storm westward. Remember that
warmer, moister air is less dense than cooler or drier air so the storm floats,
bobbling along like a giant balloon.
In an El Niño year,
which this is NOT, the easterlies fade and the storm is more likely to float
around in the Atlantic until it gets far enough north to run out of hot ocean
water.
This year, not only is
there no El Niño, but the ocean waters are extremely warm. That is why right now there are 3 active
hurricanes in the Atlantic (very unusual) and they are heading towards land in
North America.
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| From Weather Underground, https://www.wunderground.com |
Predicting the path of hurricanes
is not easy. Being giant (very
destructive) balloons, they will bounce off other storms, cold fronts, or any
other air masses that are denser.
Eventually most hurricanes move far enough north to get caught by the
prevailing westerly winds that blow across most of the US and then reach the
North Atlantic where the water is too cold to sustain the winds.
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| From Weather Underground, https://www.wunderground.com |
The latest predictions
for Irma, which have not changed much over the last 24 hours, are that it will
hit the Florida keys very early Sunday morning and then move right up the
center of Florida to Atlanta, Georgia.
It will then hit air currents that will sweep it to the west before the
westerlies bring it back over Atlanta.
There is a good chance that it will then continue northeast, passing
over Delaware before going out to sea.
Fortunately by the time it hits Atlanta for the first time it will have
been away from the ocean long enough to have lost much of its warm water energy
and will be only a tropical depression with lots of rain but winds of less than
40 mph.
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| Talk show host claims media coverage of Hurricane Irma a conspiracy by the media, then finds an excuse to leave Florida. From Business Insider: http://www.businessinsider.com |
