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Paul
Hudson
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This
month I have been researching into weather lore, prompted by a series
of spectacular sunsets and sunrises visible across much of the region.
In
fact, although the subject largely consists of 'old wives tales',
the most famous one of all is one of the most reliable around and
with sound scientific background.
Red
sky at night, Shepherds delight
There
are two explanations for this saying.
The passage of a cold front eastwards will allow the setting sun
in the west to reflect off the tops of the cloud causing a reddening
of the sky at dusk.
The
passage of a cold front causes a rise in pressure, and more especially
for eastern parts of the region, a couple of days of decent weather.
High pressure usually means fine weather. An inversion is also associated
with this, which effectively is a 'lid' on the atmosphere which
acts to trap dust and other pollutants.
The
setting sunlight is scattered by these particles, leaving the longest
wavelength, red, to illuminate the evening sky.
So,
if the sky is red, it can illustrate the inversion and high pressure
is in place and the next day often is fine.
Red
sky in the morning, Shepherds warning
Here's
one explanation for the other half of this saying.
A warm front slopes forwards, and the first hint of such an approaching
front is very high (often invisible) cirrus cloud at around 36000
feet.
As
the sun rises in the east, it reflects on this ice cloud, again
turning red as the light is scattered.
Hence
if the weather conditions are appropriate, a red sky in the morning
can mean an approaching weather front and rain in the next 12 hours.
Monthly
Statistics
January
was generally a better month than average, with mean temperatures
slightly higher than normal.
It
was also drier and sunnier than normal.
Rainfall for the month - 61mm (Long term average 87mm)
Sunshine - 55 hours (LTA 43 hours)
Daytime temperatures 7C (LTA 6.5C)
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Rainfall - 61mm
