Реферат: Climate and Weather in Great Britain (Климат и погода в Великобритании)Climate andWeather in Great Britain
Weather is not the same asclimate. The weather at a place is the state of the atmosphere there at a giventime or over a short period. The weather of the British Isles is greatlyvariable.
The climate of a place or region, onthe other hand, represents the average weather conditions over a long period oftime.
The climate of any place results from the interaction of a number ofdetermining factors, of which the most important are latitude, distance fromthe sea, relief and the direction of the prevailing winds.
Thegeographical position of the British Isles within latitudes 50oto 60oN is a basic factor in determining the maincharacteristics of the climate. Temperature, the most important climatic element, depends not onlyon the angle at which the sun’s rays strike the earth’s surface, but also onthe duration of daylight. The length of day at London ranges from 16 hours 35minutes on June to 7 hours 50 minutes on 21 December. British latitudes formthe temperate nature of the British climate, for the sun is never directlyoverhead as in the tropical areas.
Britain’sclimate is dominated by the influence of the sea. It is much milder than thatin any other country in the same latitudes. This is due partly to the presenceof the North Atlantic Drift, or the Gulf Stream, and partly to the fact thatnorth-west Europe lies in a predominantly westerly wind-belt. This means thatmarine influences warm the land in winter and cool in summer. This moderatingeffect of the sea is in fact, the cause of the relatively small seasonalcontrasts experienced in Britain.
Themoderating effect of the ocean on air temperature is also stronger in winterthan in summer. When the surface water is cooler than the air above it –as frequently happens during the summermonths – the air tends to lose itsheat to the water. The lowest layers of air are chilled and become denser bycontradiction, and the chilled air tends to remain at low levels. The surfacewater 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 isexchanged.
Oppositeconditions apply in winter. The air in winter is likely to be cooler than thesurface water, so that the heat passes from water to air. Air at low levels iswarmed and expands and rises, carrying oceanic heat with it, while the chilledsurface water contracts and sinks, to be replaced by unchilled water frombelow. This convectional overturning both of water and of air leads to avigorous exchange of heat.
Theprevailing 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. Ontheir arrival to Britain, the winds are forced upwards, and as a resultlarge-scale condensation takes place, clouds form and precipitation follows,especially over the mountainous areas.
North andnorth-west winds often bring heavy falls of snow to north Britain during lateOctober and November, but they are usually short-lived. Continental winds fromthe 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 northsea and bring cold, continental-type weather to eastern and inland districts ofGreat Britain.
Relief isthe most important factor controlling the distribution of temperature andprecipitation within Britain. The actual temperatures experienced in the hillyand mountainous parts are considerably lower than those in the lowlands. Theeffect of relief on precipitation is even more striking. Average annualrainfall in Britain is about 1,100 mm. But the geographical distribution ofrainfall is largely determined by topography. The mountainous areas of the westand north have more rainfall than the lowlands of the south and east. Thewestern Scottish Highlands, the Lake District (the Cumbrian mountains), Welshuplands and parts of Devonand Cornwall in the south-west receive more than2,000 mm of rainfall each year.
Incontrast, the eastern lowlands, lying in a rain-shadow area, are much drier andusually receive little precipitation. Much of eastern and south-eastern England(including London) receive less than 700 mm each year, and snow falls on only15 to 18 days on the average.
Rainfallis fairly well distributed throughout the year, although March to June are thedriest months and October to January are the wettest.
Irelandis in the rather a different category,for here the rain-bearing winds have not been deprived of their moisture, andmuch of the Irish plain receives up to 1,200 mm of rainfall per year, usuallyin 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 thesea and prevailing winds are equally evident in the general pattern of rainfallover the country.
Becauseof the North Atlantic Drift and predominantly maritime air masses that reachthe British Isles from the west, the range in temperature throughout the yearis never very great. The annual mean temperature in England and Wales is about10oC, in Scotland and Northern Ireland about 9oC.July and August are the warmest months of the year, and January and Februarythe coldest.
The mean winter temperature in the north is 3OC,the mean summer temperature 12oC. The correspondingfigures for the south are 5oC and 16oC. The mean Januarytemperature for London is 4oC, and the mean July temperature 17oC.
During anormal summer the temperature may occasionally rise above 30oC inthe south. Minimum temperatures of –10oC may occur on a still clearwinter’s night in inland areas.
Thedistribution of sunshine shows a general decrease from south to north – thesouth has much longer periods of sunshine than the north.
It isfrequently said that Great Britain does not experience climate, but onlyweather. This statement suggests that there is such a day-to-day variation intemperature, rainfall, wind direction, wind speed and sunshine that the “averageweather conditions”, there is usually no very great variation from year to year or between corresponding seasons ofdifferent years.
No placein Britain is more than 120 km from the sea. But although the British arecrowded very closely in a very small country, there is one respect in whichthey are very fortunate. This is their climate. Perhaps, this is a surprisingstatement because almost everyone has heard how annoying the weather usually isin England. Because of the frequent clouds and the moisture that hangs in theair 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 toenjoy it. The weather changes constantly. No ordinary person can guess from oneday to another which season he will find himself in when he wakes in themorning. Moreover, a day in January may be as warm as a warm day in July and aday in July may be as cold as the coldest in January.
Butalthough 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 seldomhot. Men ride to work on bicycles all through the year. Along the south coastEnglish gardens even contain occasional palm trees.
The mostremarkable feature of English weather, the London fog, has as exaggeratedreputation. What makes fog thick in big industrial areas is not so much themoisture in the air as the soot frommillions of coal fires. Such smogs (smoke + fog) are not frequent today. Since1965 as a result of changes in fuel usage and the introduction of clean airlegislation, they have become less severe. It is quite natural that in fine, still weather there isoccasionally haze in summer and mist and fog in winter.
Theamount of rainfall in Britain is exaggerated, too. Britain seems to have agreat deal of rain because there are so many showers. But usually very littlerain falls at a time. Often the rain is hardly more than floating mist in whichyou can hardly get wet. Although a period of as long as three weeks withoutrain is exceptional in Britain.
It is nowonder that, living in such an unbearable climate with so many rules and withstill more exceptions, the Englishmen talk about their weather, whatever it maybe, and their climate, too.
1.Baranovski L.S.,Kozikis D.D.. How Do YouDo, Britain? – Moscow ,1997.