|
A weather
forecast may not seem as important as your passport but when the
roof of your hotel is ripped off by a 150 mph gust you may change
your mind!
This
is the time of the year when many of us are thinking about booking
a fortnight in the sun. Nice hotels, sandy beaches, good food and
a favourable exchange rate are often top of the list of holiday
priorities.
But
don’t forget to check on the weather at your holiday destination.
Long-haul holidays may be cheaper than ever before but if you are
not careful you could be left with a holiday memory you could well
do without - a hurricane!
 |
| Hurricanes
feature sustained wind speeds of 150 mph |
Hurricanes
are the most destructive large-scale weather feature on the face
of the Earth.
Sustained
wind speeds of 150 miles per hour, gusts of 190 MPH and rainfall
of up 30 millimetres are some of the hazards awaiting those unlucky
enough to be caught in their path.
The
hurricane is the severest form of a tropical cyclone. To qualify
as a hurricane a cyclone must have sustained winds in excess of
74 MPH.
Such
a hurricane would qualify as a Category 1 storm on the Saffir-Simpson
Hurricane Scale. A Category 5 hurricane is the strongest with wind
speeds of more than 155 MPH.
Hurricanes
grow
Tropical
cyclones begin life as wave features in tropical areas. To grow
into hurricanes they need a complex combination of atmospheric conditions.
Crucially, sea temperatures must exceed 27 degrees Celsius.
Light
winds through the atmosphere are also necessary. As warm ocean waters
add moisture to developing storm clouds, condensation causes more
heat to be released adding to the available energy of the developing
storm.
There
are several features characteristic of all hurricanes. The eye is
an area of relatively calm, clear weather lying at the centre of
the hurricane.
The
eye of the storm
The
eyewall surrounds the eye and it is here that the strongest winds
are found. The outer rainbands have many embedded thunderstorms,
tens of miles wide and hundreds of miles in length.
The
right side of the hurricane is usually the most dangerous part of
the storm and it is here that tornadoes are likely to form.
Whist
winds and rain are generally seen as the major hazards, the greatest
threat to life and property is the storm surge.
The
storm surge
A huge
dome of water, one hundred miles wide and up to fifteen feet high
swells up in response to the low atmospheric pressure. When this
hits a coastline massive waves can sweep inland for several miles
leaving a trail of devastation in their wake.
All
cyclones which reach hurricane status are given a name. The names
of the most destructive hurricanes (such as Andrew and Gilbert)
are usually retired.
During
this year’s hurricane season (between 1st June and 30th November)
we can expect to see (in alphabetical order) Arthur, Dolly, Sally
[What! No Susan] and Wilfred to name but a few.
We
are most familiar with hurricanes of the Atlantic and Caribbean.
But similar storms are found in the Pacific and China Seas where
they are known as typhoons, and in the Indian Ocean where they are
known as cyclones.
Predicting
a hurricane
The
good news is that despite the seemingly random meander of hurricanes,
numerical weather prediction has given some excellent advanced warning
of the approach of many hurricanes. As a result the death tolls
from these storms are continuing to fall.
|
The storm surge is a huge
dome of water, one hundred miles wide and up to fifteen feet
high swells up in response to the low atmospheric pressure.
When this hits a coastline massive waves can sweep inland
for several miles leaving a trail of devastation in their
wake.
|
| Richard
Angwin |
So
before you head off for that bargain break to Florida, the Dominican
Republic or Northern Australia what can you do to ensure you are
not heading into the path of one of these monsters?
General
information on the climate for selected destinations can be found
on these weather pages.
The
BBC Weather site offers five day forecasts for most destinations
plus general climate information. As this site is linked to the
Met Office’s supercomputer, the forecasts are usually very
reliable.
The
Met Office’s own website provides a wealth of information including
extreme weather events.
Other sites include that of the National Hurricane Center in Florida
and, for more general hurricane information, the University of Illinois.
by
Richard Angwin
|
