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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