Modern Geography

ther, may appear to occur without order or regularity, but detailed quantitive study soon shows that even British weather displays cons

duced to abandon his rule that such and such operations must not be undertaken before certain fixed dates. The farmer, if he is to avoid ban

accurate form, leads us to the conclusion that for every locality on the earth's surface

But it should be understood that such figures can be used by the geographer with justification only when he is himself aware, and can assume that his audience is aware, of the significance of the figures in connection with the processes of erosion and the phenomena of life. To say that the mean January tempera

hat will be attempted, therefore, is to discuss one or two important climates with the object of considering later their respective effects on the distribution of othe

where the extraordinarily regular winds called "trades" blow, have of course been known for long enough. But not till the latter half of the nineteenth century did the civilised nations begin regular meteorological observations, and these o

ment and has been most studied round the Mediterranean area. But it also occurs in California, in parts of Chile, in South Africa round Cape Colony, and in south and south-western Australia. Generally, it is characteristic of lands lying on the western side of continents,

of the Mediterranean area two introduced American plants, the agave and the prickly pear, are more obvious and abundant than most

season further north, which is here largely a period of cessation of plant growth. The rain, which tends to be scanty or even absent in the interior of land masses, e. g. in Spain and Asia Minor, and also

interesting as the fact itself, and to understand it we must

eloped over the largest area, and where, for many reasons, it is most important. But it must be noted that the conditions which give rise to the Mediterranean type of climate are

nd light winds or calms, coincide with the equator. In the northern summer it moves north with the sun; in the northern winter it travels south with the sun, being always over what is called the heat equator. Into this belt of low pressure air from north and south, where the pressure is greater, tends to rush in, and we have thus formed the co

10° to 15° further south. A glance at the map, then, will show that in summer the Mediterranean area is within or near the sp

n the direction known as counterclockwise, that is, in the direction opposite to that of the hands of the clock. The result is the production of the winds which appear off the coast of western Europe as the warm south-westerly winds of winter, while

c they arrive off Europe saturated with moisture. As they come from lower latitudes they are warmth bringing. In winter these winds reach the Mediterranean area owing to the southern shift of the t

bout the 40th parallel of latitude, though it varies according to local conditions in the different peninsulas

a zone of variable winds, but in general terms we can explain the peculiarities of the Mediterranean rainfall by saying that

alves of all the great peninsulas. Quite generally, however, we may say that the northern limit of the Mediterranean region, in its western half, is defined by the occurrence of considerable summer rain. That is, it is bounded to the north by a region which is within reach of the rain-bringing anti-trades in summer as well as in winter, and which has a lower

d to the action of drying winds, and its rainfall is therefore small or nil. Similarly in California the southern limit of the Mediterranean zone of climate is the desert region of Arizona, Mex

rain at all, or, to the north, small amounts. To the north the region passes gradually into that colder zone where rain occurs abundantly both in summer and winter, while to the east and south the rainfall diminishes greatly, and there is a gradual transition to desert conditions. To the west the boundary of the region is theoretically the ocean, but the wes

there are other features of the Mediterranean climate which are almost as important in considering the ef

red, are relatively rare within the limits of the Mediterranean region. Looking at the same fact from the human standpoint we may say that the rainfall is often so scanty that irrigation is necessary before man can prosper. These two facts, that Mediterranean man had not to clear forests before he planted and sowed, as the Teutons were obliged to do, and that he had often to b

nter exceptionally mild, while the summers, though not excessively hot they are considerably cooler than those of similar latitudes in Asia, are yet warm and sunny. The result is that, given water artificially supplied, or given crops which can

annual rainfall of about 28 inches, and London one of about 25 inches. In other words, when the total amount of rain which falls in any one year is estimated for many years in either of these places, these totals ad

in passing from west to east, and in passing from north to south. Thus Gibraltar, at one end of the basin has a fall of 32" per annum, as c

d London we must remember that the higher temperatures mean much greater evaporation. Sunny Naples has abou

. In July the mean temperature at London is 62°, as against 73° at Nice and over 80° at Athens. In other words, owing to our mild winters and cool summers, there is far more difference between British and Mediterranean temperatures in summer than in winter. In the Mediterranean region itself the difference between the temperatures

n example of the methods and results of modern climatology. We may note mu

esert conditions tending to supervene. Still further east, however, we come to a region where the rainfall is abundant, and where the population is once mo

west and the other to the south-east, separated from each other by warm and cold deserts. Each of these two regions has given rise to its own civilisation, each has p

dry. Whereas, then, in the Mediterranean the heat of summer is largely wasted, from the agriculturist's point of view, on account of the scarcity of the water necessary for growth, in monsoon regions, unless the rain fail, as it sometimes does, the hot season is the moist season, and, therefore, other things being equal, growth must be faster h

tropics we find that the total fall increases, and tends to show two maxima, which occur when the sun is overhead, i. e. at the equinoxes. For our particular purpose, however, the climatic conditions in tropical and e

ower than in the Mediterranean basin, and winter frost plays an important part in determining the choice of cultivated plants. As the figures which we have already quoted for London and Paris suggest, the winter cold increases on passing eastward. Paris is colder in winte

speaking generally, a moderating influence upon climate, producing the so-called maritime climate. In the case of the British Isles this effect is very marked, because the ocean to the west of us is unusually warm, and the circula

es not depend upon latitude alone, but may be greatly modified by local conditions

arm summers, where the rain tends to fall during the winter season, making summer a period of drought. This climate extends beyond the limits of Europe into North

distributed throughout the year. On passing inwards this type of climate changes into the continental type, with cold winters and hot summers, and diminishing rainfall. Though precipitation occu

ope, we may realise that the climates of North America show a remarkable analogy to the European. On the western side we have in British Columbia and California respectively the same two ty

astern North America. The result is that we find that Labrador, though lying in the latitude of Great Britain, has a very severe climate. Further south the conditions are of the "continental" character even on the seaboard, the winters being very cold and the summers hot. Rainfall is equally distributed throughout the year, but on passing inland it diminishes in amount and tends to be limited to the war

mate than the western, offering in this respect an analogy to the conditions which prevail on the eastern and wes

that the different averages are based upon varying numbers of observations, and are therefore not strictly comparable with one another. There is always a risk that such figures may mask facts of real geographical importance. No doubt some of the difficulties will disappear with the progress of meteorological science, which will enable the geographer only to sel

y in the direction known as counterclockwise, and are represented by the arrows whose double barbs signify their strength. It will be noted that in the rear of the cyclone the winds are northerly. They thus chill the air here, and by chilling it raise the pressure. The winds to

a proverb on account of its variableness, as

y come to us from the Atlantic, and continue eastwards past us, often towards the Baltic. We have already noted the occurrence of what we have called a permanent area of

r, while the onward movement of the air in front of the depression lowers the pressure there, and so produces displacement. Again, the air is sucked into a depression in the direction opposite to the hands of a clock, and a moment's reflection will show that this means that the winds to the east of the de

are feeling the effects of the colder winds in its rear. If the thermometer suddenly rises again, then a new depression is approaching, and we are feeling its warm breath before its winds reach us. Th

is that they seem to prefer damp air, and so tend to follow the

an speed of about 16 miles an hour, while in the United States their mean speed is 25 miles per hour,

mild and windy winters. In summer they travel further northwards, and as a rule affect our climate less. When, however, from causes still

an important element in protecting the British Islands from foreign invasion, while we

e wind is southerly and light (arrows with single barbs) and the temperature high. As it passes the winds become violent (arrows with double barbs), and shift to the south-west, and the barometer falls rapidly. As it disappears the pressure rises,

e at some part of our area of anticyclones, or areas of high pressure, out

and in winter. In winter they may bring to us the continental cold, and make our weather abnormally severe, though often bright and fine. On the other hand, in summer they bring to us continental warmth, so that "good" summers are those in which anticyclonic conditions are most frequent

avel too far north or too far south to influence our weather. It is possible that further investigation in the future may unravel this problem; it is practically certain that a freer

a, and into it the winds are sweeping strongly in a counterclockwise direction. An anticycl

tself it will form the subject of a special volume in this series. It may be enough to point out that the Daily Weather Report, published by the Meteorologic