The climate of a country or district is, briefly, the average weather of that country or district, and it depends upon various factors, all mutually interacting, upon the latitude, the temperature, the direction and strength of the winds, the rainfall, the character of the soil, and the proximity of the district to the sea.

The differences in the climates of the world depend mainly upon latitude, but a scarcely less important factor is proximity to the sea. Along any great climatic zone there will be found variations in proportion to this proximity, the extremes being “continental” climates in the centres of continents far from the oceans, and “insular” climates in small tracts surrounded by sea. Continental climates show great differences in seasonal temperatures, the winters tending to be unusually cold and the summers unusually warm, while the climate of insular tracts is characterised by equableness and also by greater dampness. Great Britain possesses, by reason of its position, a temperate insular climate, but its average annual temperature is much higher than could be expected from its latitude. The prevalent south-westerly winds cause a drift of the surface-waters of the Atlantic towards our shores, and this warm-water current, which we know as the Gulf Stream, is the chief cause of the mildness of our winters.

Most of our weather comes to us from the Atlantic. It would be impossible here within the limits of a short chapter to discuss fully the causes which affect or control weather changes. It must suffice to say that the conditions are in the main either cyclonic or anticyclonic, which terms may be best explained, perhaps, by comparing the air currents to a stream of water. In a stream a chain of eddies may often be seen fringing the more steadily-moving central water. Regarding the general north-easterly moving air from the Atlantic as such a stream, a chain of eddies may be developed in a belt parallel with its general direction. This belt of eddies or cyclones, as they are termed, tends to shift its position, sometimes passing over our islands, sometimes to the north or south of them, and it is to this shifting that most of our weather changes are due. Cyclonic conditions are associated with a greater or less amount of atmospheric disturbance; anticyclonic with calms.

The prevalent Atlantic winds largely affect our island in another way, namely in its rainfall. The air, heavily laden with moisture from its passage over the ocean, meets with elevated land-tracts directly it reaches our shores—the moorland of Devon and Cornwall, the Welsh mountains, or the fells of Cumberland and Westmorland—and blowing up the rising land-surface, parts with this moisture as rain. To how great an extent this occurs is best seen by reference to the map of the annual rainfall of England on the next page, where it will at once be noticed that the heaviest fall is in the west, and that it decreases with remarkable regularity until the least fall is reached on our eastern shores. Thus in 1906, the maximum rainfall for the year occurred at Glaslyn in the Snowdon district, where 205 inches of rain fell; and the lowest was at Boyton in Suffolk, with a record of just under 20 inches. These western highlands, therefore, may not inaptly be compared to an umbrella, sheltering the country further eastward from the rain.

The above causes, then, are those mainly concerned in influencing the weather, but there are other and more local factors which often affect greatly the climate of a place, such, for example, as configuration, position, and soil. The shelter of a range of hills, a southern aspect, a sandy soil, will thus produce conditions which may differ greatly from those of a place—perhaps at no great distance—situated on a wind-swept northern slope with a cold clay soil.

Berkshire is an inland county but no part of it is as much as 75 miles from the coast. The chalk downs have a fine bracing climate, and though some of the valleys may be relaxing and some of the moorland tracts bleak, the general climate of the county is exceedingly healthy. Compared with the south coast of England Berkshire is rather cooler, with somewhat less sunshine and less rain than the coast.

Temperature, it should be remarked, varies according to height above sea level, falling about 1° Fahr. for each 100 to 300 feet upwards. In a comparatively level district, like Berkshire, this is not a very serious consideration. The mean temperature for the year varies in different parts of England from about 47·3 in the north-eastern counties to about 49·6 in the south-east. The mean temperature is about 49·0 in northern Berkshire and about 47·5 in south-western Berkshire. It may be of interest to give the mean temperature for one year at places in and close around Berkshire. We take the year 1907 and the figures are as follows—Maidenhead 49·4, Wokingham 47·7, Swarraton in Hampshire 47·9, Marlborough in Wiltshire 47·4, and Oxford 48·9.

The average temperature in the month of January varies from 37·0 to 38·0 in different parts of the county, and the average temperature for July from 59·7 to 62·0.

In England bright sunshine is most prevalent on the coast and decreases inland. The annual total amount for the south and east coast from Cornwall to Norfolk is nearly 1800 hours, whilst in the northern midland counties the amount is about 1200 hours. There are no definite data available for giving the amount for Berkshire, but there are probably about 1500 hours of bright sunshine in the year.

The rainfall varies a good deal in different parts of the county. The amount is lowest in the north-east and highest in the south-west. Thus Wallingford and Cookham have a rainfall of about 23 inches a year on an average. At Reading, which is somewhat to the south-west, the amount is nearly 24 inches a year, and on a line running through Wellington College and Yattendon the amount is nearly 25 inches. Letcombe Regis and Ashbury have a rainfall of between 25 and 26 inches. At Faringdon the figure is above 26, and in the south-western corner of the county there is a rainfall of about 29 inches a year. The average yearly rainfall for the whole of England is 31·62 inches, and for the British Isles it is 39·25 inches. Looking at the extremes of rainfall in England we find the lowest at Shoeburyness with an average of 19·7 inches for the year, whilst Seathwaite in Cumberland has an average rainfall of 133·53 inches per annum.