The difficulty of sharply delimiting edaphic and climatic factors is seen in the case of temperature.
Many of the great historic movements of peoples were doubtless due to the gradual change of geographical or climatic conditions; and the slow desiccation of Central Asia has been plausibly suggested as the real cause of the peopling of modern Europe and of the medieval wars of the Old World, the theatres of which were critical points on the great natural lines of communication between east and west.
The nature of the soil appears, however, to be of secondary importance, provided that it is able to hold moisture and that climatic conditions of high and even temperature with considerable rainfall and absence of wind are satisfied.
To 44.4 The climatic conditions of the western districts of the state are entirely different from those of the other two regions.
Diogenes made this conception of a vital and intelligent air the ground of a teleological view of climatic and atmospheric phenomena.
The development of man is explained in connexion with that of the earth, and in relation to climatic variations, &c.
For instance, a Fungus epidemic is impossible unless the climatic conditions are such as to favor the dispersal and germination of the spores; and when plants are killed off owi~ig to the supersaturation of the soil with water, it is by no means obvious whether the excess of water and dissolved materials, or the exclusion of oxygen from the root-hairs, or the lowering of the temperature, or the accumulation of foul products of decomposition should be put into the foreground.
For example, rae Arenarion in one climatic or geographical region might be in~~ med an a-Arenarion and one in a different region a a-Arena- ~j1j ri, and so on (Moss, bc. cit.).
Such groups are interesting in that they are vegetation units whose physiognomy is, in a broad sense, related more to climatic than to edaphic conditions.
Hence, in any cosmopolitan treatment of vegetation, it is necessary to consider the groups of plant communities from the standpoint of the climatic or geographical district in which they occur; and this indeed is consistently done by Schimper.
Finally, within any district of constant or fairly constant climatic conditions, it is possible to distinguish plant communities which are related chiefly to edaphic or soil conditions; and the vegetation units of these definite edaphic areas are the plant formations of some writers, and, in part, the edaphic formations of Schimper.
In external habit these exhibit adaptations to every kind of climatic or physical condition:
The evidence which has thus been briefly summarized, points unmistakably to the conclusion that existing vegetation originated in the northern hemisphere and under climatic conditions corresponding to what would now be termed sub-tropical.
In regions where climatic conditions are favourable, cotton grows more or less successfully on almost all kinds of soil; it can be grown on light sandy soils, loams, heavy clays and sandy " bottom " lands with varying success.
Queensland, New South Wales and South Australia possess suitable climatic conditions, and in the first-named state the cotton has been grown on a commercial scale in past years, the crop in 1897 being about 450 bales.
It is thinly wooded, except in the north, where the climatic conditions approach those of the Amazon valley.
These arrangements have doubtless some reference to climatic phenomena, continuity of growth being arrested by cold and promoted by warmth.
The prevailing winds, mild and humid, are west winds from the Atlantic; continental climatic influence makes itself felt in the east wind, which is frequent in winter and in the east of France, while the mistral, a violent wind from the north-west, is characteristic of the Mediterranean region.
In reality, however, it experiences fewer climatic variations than the other great continents, owing to its distance (28°) from the Antarctic circle and (11°) from the equator.
Equally disastrous are those climatic or seasonal changes which involve temperatures in themselves not excessive but in wrong sequence; how many more useful plants could be grown in the open in the United Kingdom if the deceptively mild springs were not so often followed by frosts in May and June!
Breakages and abrasions due to wind, snow, lightning, and other climatic agents.
Physical FactorsThese are frequently classified as edaphic or soil factors and climatic factors; but there is no sharp line of demarcation between them.
The indirect geographical elements, which, as a rule, act with and intensify the direct, are mainly climatic; the prevailing winds, rainfall, mean and extreme temperatures of every locality depending on the arrangement of land and sea and of land forms. Climate thus guided affects the weathering of rocks, and so determines the kind and arrangement of soil.
Of this line it is customary to distinguish several zones, lying, generally, parallel to it, and, differentiated chiefly by climatic differences.
The maximum gradient possible depends on climatic conditions, a dry climate being the most favourable.
Eaton discovered on the desolate shores of Kerguelen's 'Island apterous and semi-apterous Diptera (Tipulidae and jEph_ydridae) of a degraded type adapted to the climatic peculiarities of the locality.
This evidence of a gradual process of upheaval still in action may throw some light on the physical (especially the climatic) changes which must have passed over that part of Asia since Balkh was the " mother of cities," the great trade centre of Asia, and the plains of Balkh were green with cultivation.
The foregoing brief review of the principal territorial divisions according to which the forms of life are distributed in Asia, indicates how close is the dependence of this distribution on climatic conditions, and this will be made more apparent by a somewhat fuller account of the main features of the flora and fauna.
Various climatic factors may cause temporary checks, but the growing and maturing period is sufficiently long to allow the plants to overcome these disturbances.
- Climatic conditions in Egypt differ radically from those in the United States, the rainfall being so small as to be quite insufficient for the needs of the plant, very little rain indeed falling in the Nile Delta during the whole growing season of the crop: yet Egypt is in order the third cottonproducing country of the world, elaborate irrigation works supplying the crop with the requisite water.
The improvements desired in cotton vary to some degree in different countries, according to the present character of the plants, climatic conditions, the chief pests, special market requirements, and other circumstances.
As an instance of the influence of climatic conditions combined with high cultivation the cane lands of the Sandwich Islands may be cited.
The flora of Venezuela covers a wide range because of the vertical climatic zones.
West and north of the Drakensberg the general level of the low veld is not much below that of the lowest altitudes of the middle veld, though the climatic 1 By the Boers the western and less elevated part of the plateau is known as the middle veld.
At Santos the rainfall is exceptionally heavy and the mean temperature high, but below that point the climatic conditions are considerably modified, the range in temperature being greater, the mean annual temperature lower, and the rainfall more evenly distributed throughout the year.
The rainfall throughout this region is abundant, except in northern Minas Geraes, where the climatic conditions are influenced to some extent by the arid eastern plateau.
In spite of somewhat adverse climatic conditions, live stock is reared with a fair amount of success.
==Fauna== The three climatic regions of Alberta have naturally a varying fauna.
As Clement Reid remarked: World-wide floras, such as seem to characterize some of the older periods, have ceased to be, and plants are distributed more markedly according to geographical provinces and in climatic zones.
Climatic factors include all those relating to atmospheric temperature, rainfall, atmospheric humidity, and light and shade.
The types of vegetation (tropical forests, sclerophyllous forest, temperate forests, tundra, &c.) thus briefly outlined are groups of Schimpers climatic formations.
The climatic conditions in the British Islands are such that it is not possible to maintain, in unfavourable weather, a higher standard than that named, which is the insulation obtained when all the insulators are in perfect condition and only the normal leakage, due to moisture, is present.