Climate and
Weather in Great Britain
Weather is not the same as
climate. The weather at a place is the state of the atmosphere there at a given
time or over a short period. The weather of the British Isles is greatly
variable.
The climate of a place or region, on
the other hand, represents the average weather conditions over a long period of
time.
The climate of any place results from the interaction of a number of
determining factors, of which the most important are latitude, distance from
the sea, relief and the direction of the prevailing winds.
The
geographical position of the British Isles within latitudes 50o to 60o N is a basic factor in determining the main
characteristics of the climate. Temperature, the most important climatic element, depends not only
on the angle at which the sun’s rays strike the earth’s surface, but also on
the duration of daylight. The length of day at London ranges from 16 hours 35
minutes on June to 7 hours 50 minutes on 21 December. British latitudes form
the temperate nature of the British climate, for the sun is never directly
overhead as in the tropical areas.
Britain’s
climate is dominated by the influence of the sea. It is much milder than that
in any other country in the same latitudes. This is due partly to the presence
of the North Atlantic Drift, or the Gulf Stream, and partly to the fact that
north-west Europe lies in a predominantly westerly wind-belt. This means that
marine influences warm the land in winter and cool in summer. This moderating
effect of the sea is in fact, the cause of the relatively small seasonal
contrasts experienced in Britain.
The
moderating effect of the ocean on air temperature is also stronger in winter
than in summer. When the surface water is cooler than the air above it –
as frequently happens during the summer
months – the air tends to lose its
heat to the water. The lowest layers of air are chilled and become denser by
contradiction, and the chilled air tends to remain at low levels. The surface
water expands because it is warmed, and remains on the surface of the ocean.
Unless the air is turbulent, little of it can be cooled, for little heat is
exchanged.
Opposite
conditions apply in winter. The air in winter is likely to be cooler than the
surface water, so that the heat passes from water to air. Air at low levels is
warmed and expands and rises, carrying oceanic heat with it, while the chilled
surface water contracts and sinks, to be replaced by unchilled water from
below. This convectional overturning both of water and of air leads to a
vigorous exchange of heat.
The
prevailing winds in the British Isles are westerlies. They are extremely moist,
as a result of their long passage over warm waters of the North Atlantic. On
their arrival to Britain, the winds are forced upwards, and as a result
large-scale condensation takes place, clouds form and precipitation follows,
especially over the mountainous areas.
North and
north-west winds often bring heavy falls of snow to north Britain during late
October and November, but they are usually short-lived. Continental winds from
the east sometimes reach the British Isles in summer as a warm, dry air-stream,
but they are more frequently experienced in winter when they cross the north
sea and bring cold, continental-type weather to eastern and inland districts of
Great Britain.
Relief is
the most important factor controlling the distribution of temperature and
precipitation within Britain. The actual temperatures experienced in the hilly
and mountainous parts are considerably lower than those in the lowlands. The
effect of relief on precipitation is even more striking. Average annual
rainfall in Britain is about 1,100 mm. But the geographical distribution of
rainfall is largely determined by topography. The mountainous areas of the west
and north have more rainfall than the lowlands of the south and east. The
western Scottish Highlands, the Lake District (the Cumbrian mountains), Welsh
uplands and parts of Devon
and Cornwall in the south-west receive more than
2,000 mm of rainfall each year.
In
contrast, the eastern lowlands, lying in a rain-shadow area, are much drier and
usually receive little precipitation. Much of eastern and south-eastern England
(including London) receive less than 700 mm each year, and snow falls on only
15 to 18 days on the average.
Rainfall
is fairly well distributed throughout the year, although March to June are the
driest months and October to January are the wettest.
Ireland
is in the rather a different category,
for here the rain-bearing winds have not been deprived of their moisture, and
much of the Irish plain receives up to 1,200 mm of rainfall per year, usually
in the form of steady and prolonged drizzle. Snow, on the other hand, is rare,
owing to the warming effects of the Gulf Stream. The combined influences of the
sea and prevailing winds are equally evident in the general pattern of rainfall
over the country.
Because
of the North Atlantic Drift and predominantly maritime air masses that reach
the British Isles from the west, the range in temperature throughout the year
is never very great. The annual mean temperature in England and Wales is about
10oC , in Scotland and Northern Ireland about 9oC.
July and August are the warmest months of the year, and January and February
the coldest.
The mean winter temperature in the north is 3OC,the mean summer temperature 12oC. The corresponding
figures for the south are 5oC and 16oC. The mean January
temperature for London is 4oC, and the mean July temperature 17oC.
During a
normal summer the temperature may occasionally rise above 30oC in
the south. Minimum temperatures of –10oC may occur on a still clear
winter’s night in inland areas.
The
distribution of sunshine shows a general decrease from south to north – the
south has much longer periods of sunshine than the north.
It is
frequently said that Great Britain does not experience climate, but only
weather. This statement suggests that there is such a day-to-day variation in
temperature, rainfall, wind direction, wind speed and sunshine that the "average
weather conditions”, there is usually no very great variation from year to year or between corresponding seasons of
different years.
No place
in Britain is more than 120 km from the sea. But although the British are
crowded very closely in a very small country, there is one respect in which
they are very fortunate. This is their climate. Perhaps, this is a surprising
statement because almost everyone has heard how annoying the weather usually is
in England. Because of the frequent clouds and the moisture that hangs in the
air even on fairly clear days, England has less sunshine than most countries,
and the sunlight is weaker then in other places where the air is dry and clear.
What is worse, sunshine rarely lasts long enough for a person to have time to
enjoy it. The weather changes constantly. No ordinary person can guess from one
day to another which season he will find himself in when he wakes in the
morning. Moreover, a day in January may be as warm as a warm day in July and a
day in July may be as cold as the coldest in January.
But
although the English weather is more unreliable than any weather in the world,
the English climate – average weather –
is a good one. English winters are seldom very cold and the summers are seldom
hot. Men ride to work on bicycles all through the year. Along the south coast
English gardens even contain occasional palm trees.
The most
remarkable feature of English weather, the London fog, has as exaggerated
reputation. What makes fog thick in big industrial areas is not so much the
moisture in the air as the soot from
millions of coal fires. Such smogs (smoke + fog) are not frequent today. Since
1965 as a result of changes in fuel usage and the introduction of clean air
legislation, they have become less severe. It is quite natural that in fine, still weather there is
occasionally haze in summer and mist and fog in winter.
The
amount of rainfall in Britain is exaggerated, too. Britain seems to have a
great deal of rain because there are so many showers. But usually very little
rain falls at a time. Often the rain is hardly more than floating mist in which
you can hardly get wet. Although a period of as long as three weeks without
rain is exceptional in Britain.
It is no
wonder that, living in such an unbearable climate with so many rules and with
still more exceptions, the Englishmen talk about their weather, whatever it may
be, and their climate, too.
Literature
1.Baranovski L.S.,
Kozikis D.D.. How Do You
Do, Britain? – Moscow ,1997.
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