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Freezing
rain is a rare and rather unique form of rain, one which, when experienced,
is unlikely to be forgotten in a hurry.
The
30th December 1995 was a day I shall always remember. It had looked
like we were in for an afternoon and evening of sleet and snow.
But it soon became apparent that far worse was to come.
Many
roads in the West Country became impassable - even the M5 motorway
was closed for a time and the situation was made even worse
by fallen trees, brought down by the weight of ice. |
| Richard
Angwin |
When
rain falls onto frozen roads it can quickly form black ice - and
we all know how bad that can be.
But
just imagine how much worse it can be if the rain itself is below
freezing when it hits the road - and it can happen if the rain is
supercooled. The result is a road which instantly turns into an
ice rink.
That's
what happened around lunchtime on that day. As rain fell it formed
a layer of ice upon contact with buildings, cars, pavements and
roads. Any form of movement outdoors became difficult and dangerous
within an hour.
In
fact, many roads in the West Country became impassable - even the
M5 motorway was closed for a time and the situation was made even
worse by fallen trees, brought down by the weight of ice.
Freezing
rain is a notoriously difficult thing to predict. It requires just
the right combination of warm air aloft through which rain falls.
But close to the ground there needs to be some very cold air which
cools the water droplets to below freezing, without turning them
into snow crystals.
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| Freezing
rain causes black ice on the roads |
It
took about three days for the ice to finally melt - I know because
I was stranded in the Weather Centre in Bristol for those three
days.
Freezing
rain is relatively common over large land masses, such as North
America and Continental Europe. We might be lucky here and not see
what's been dubbed 'the weather from hell' for several years.
So
if you hear weather forecasters mentioning that particular ‘F'
word in their forecasts in future - then you have been warned!
by
Richard Angwin
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