hat determine different savours,Bresil Pas Cher. But these have been explained in another treatise,PJS Herreklær Perfect Vest Norge Salg.
We have now given an account of waters and the sea,Kurtki Woolrich, why they persist,Belstaff Icon Jackor, how they change, what their nature is, and have explained most of their natural operations and affections.
4
Let us proceed to the theory of winds. Its basis is a distinction we have already made. We recognize two kinds of evaporation,Canada Goose Jacka, one moist,PJS Herreklær Schroeder Parkas Norge Salg, the other dry. The former is called vapour: for the other there is no general name but we must call it a sort of smoke,Maillot Muller Pas Cher, applying to the whole of it a word that is proper to one of its forms. The moist cannot exist without the dry nor the dry without the moist: whenever we speak of either we mean that it predominates. Now when the sun in its circular course approaches, it draws up by its heat the moist evaporation: when it recedes the cold makes the vapour that had been raised condense back into water which falls and is distributed through the earth. (This explains why there is more rain in winter and more by night than by day: though the fact is not recognized because rain by night is more apt to escape observation than by day.) But there is a great quantity of fire and heat in the earth, and the sun not only draws up the moisture that lies on the surface of it,Belstaff Maldon Kurtki, but warms and dries the earth itself. Consequently, since there are two kinds of evaporation, as we have said, one like vapour, the other like smoke,Menn Moncler Karak Norge Salg, both of them are necessarily generated. That in which moisture predominates is the source of rain, as we explained before, while the dry evaporation is the source and substance of all winds. That things must necessarily take this course is clear from the resulting phenomena themselves, for the evaporation that is to produce them must necessarily differ; and the sun and the warmth in the earth not only can but must produce these evaporations.
Since the two evaporations are specifically distinct, wind and rain obviously differ and their substance is not the same, as those say who maintain that one and the same air when in motion is wind, but when it condenses again is water. Air,Menn Moncler Reynold Norge Salg, as we have explained in an earlier book, is made up of these as constituents. Vapour is moist and cold (for its fluidity is due to its moistness, and because it derives from water it is naturally cold, like water that has not been warmed): whereas the smoky evaporation is hot and dry. Hence each contributes a part,arctic parka, and air is moist and hot. It is absurd that this air that surrounds us should become wind when in motion,Hambourg Pas Cher, whatever be the source of its motion on the contrary the case of winds is like that of rivers. We do not call water that flows anyhow a river, even if there is a great quantity of it, but only if the flow comes from a spring. So too with the winds; a great quantity of air might be moved by the fall of some large object without flowing from any source or spring.
The facts bear out our theory. It is because the evaporation takes place uninterruptedly but differs in degree and quantity that clouds and winds appear in their nat
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