قراءة كتاب The Rain Cloud or, An Account of the Nature, Properties, Dangers and Uses of Rain in Various Parts of the World

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‏اللغة: English
The Rain Cloud
or, An Account of the Nature, Properties, Dangers and Uses of Rain in Various Parts of the World

The Rain Cloud or, An Account of the Nature, Properties, Dangers and Uses of Rain in Various Parts of the World

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دار النشر: Project Gutenberg
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distribution of the waters I am speaking of, that there is more than a scanty, bare provision, a mere sufficiency; even a plenty, a surplusage of this useful creature of God, the fresh waters afforded to the world; and they so well ordered, as not to drown the nations of the earth, nor to stagnate, stink, and poison, or annoy them; but to be gently carried through convenient channels back again to their grand fountain the sea; and many of them through such large tracts of land and to such prodigious distances, that it is a great wonder the fountains should be

high enough, or the seas low enough, ever to afford so long a conveyance.” [18]

If rain is not at all seasons pleasant and delightful, neither are rain-clouds among the most beautiful which diversify the landscape of the sky; for it has been well remarked, that “all the fine-weather clouds are beautiful, and those connected with rain and wind mostly the reverse.”  What, indeed, can be more striking than the aërial landscapes of fine weather, in which, by an easy fancy, we can trace trees and towers, magnificent ruins and glaciers, natural bridges and palaces, all dashed with torrents of light or frowning in shadow, glowing like burnished silver, glittering in a golden light, or melting into the most enchanting hues?  But with all this beauty the eye is seldom capable of judging correctly of the proper size and forms and motions of clouds.  The same cloud which to one observer may be glowing with light, to another may be enveloped in shadow.  That which appears to be its summit may be only a portion of its outer edge, while that which seems to be its lower bed may really be a portion of its further border.  A spectator, on the summit of a

tall cliff, may observe what he takes to be a single cloud; while a second spectator, on lower ground, will perceive that there are two clouds.  The motions of clouds are so deceptive, that they often seem to be moving in a curve over the great concave of heaven, while they are in fact advancing in nearly a right line.  Suppose, for example that a cloud is moving from the distant horizon

towards the place where we stand, in a uniform horizontal line without changing either in size or form.  Such a cloud, when first seen, will appear to be in contact with the distant horizon, and consequently much nearer to us than it really is.  As it advances towards us, it will seem to rise into the sky, and to become gradually larger till it is almost directly overhead.  Continuing its progress, it will then seem again to descend and to lessen in size as gradually as it had before increased; till at length it disappears in the distant horizon at a point exactly opposite to that at which it was first seen.  Thus the same cloud, without varying its motion in the least from a straight line, and remaining throughout of the same size and form, would seem to be continually varying in magnitude; and the line of its motion, instead of being straight, would appear to be curved.  This is one of the most simple cases that can be supposed: but the clouds as they exist in nature do not remain of the same magnitude, but are constantly changing in form, in size, in direction, and in velocity; so that it is quite impossible to form an accurate idea of their shape and size, or to explain their motions.  Clouds, at different elevations,

may often be seen to move in different directions under the influence of different currents of wind.

Different appearance of the same clouds to different observers

The distribution of light and shade in clouds is most striking.  The watery particles of which they are composed, yielding constantly to changes in temperature and moisture, are always changing; so that a most beautiful cloud may alter in figure and appearance in an instant of time; the light parts may suddenly become dark, and those that were shaded may all at once glow in the rays of the sun.  Again, the appearance of a cloud, with respect to the sun, may entirely alter its character.  The same cloud, to one observer, may appear entirely in shade, to another tipped with silver; to a third it may present brilliant points and various degrees of shade, or one of its edges only may appear illuminated; sometimes the middle parts may appear in shadow, while the margin may be partially luminous, rendering the middle parts all the more obscure by the contrast.

A wonderful variety may also be produced by the shadow of one cloud falling upon another.  The accompanying sketch furnishes an example of this.  Sometimes the whole of a cloud projects a shadow through the air upon some other far

distant cloud, and this again upon another, until at length it reaches the ground.  The shadows of moving clouds may often be traced upon the ground, and they contribute greatly to modify the appearance of the landscape.  A large number of small flickering clouds produce broken lights and shades which have an unpleasant jarring effect; but when the clouds are massive, or properly distributed,

the shadows often produce a high degree of repose.

Shadows of clouds

Clouds are often seen to advantage in mountainous countries.  Here the aspect of the heavens may be entirely different at different elevations.  A single cloud in the valley may conceal the whole of the upper sky from an observer; but as he ascends he may gradually get above this and other layers or bands of cloud, and see a beautifully variegated sky above him, while the clouds which conceal the valley may be rolling at his feet.  Evelyn, in his Memoirs, notices a scene of this kind.  He says,—“Next morning we rode by Monte Pientio, or, as vulgarly called, Monte Mantumiato, which is of an excessive height, ever and anon peeping above airy clouds with its snowy head, till we had climbed to the inn at Radicofany, built by Ferdinand the greate Duke for the necessary refreshment of travellers in so inhospitable a place.  As we ascended we entered a very thick, solid, and dark body of cloudes, which looked like rocks at a little distance, which lasted neare a mile in going up; they were dry, misty vapours, hanging undissolved for a vast thicknesse, and obscuring both sun and earth, so that we

seemed to be in the sea rather than in the cloudes, till, having pierced through it, we came into a most serene heaven, as if we had been above all human conversation, the mountain appearing more like a great island than joyn’d to any other hills, for we could perceive nothing but a sea of very thick cloudes rowling under our feete like huge waves, every now and then suffering the top of some other mountain to peepe through, which we could discover many miles off: and betweene some breaches of the cloudes we could see landskips and villages of the subjacent country.  This was one of the most pleasant,

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