Thundercloud

“ Just that one glimpse I had of them, and no more; then the rift in the clouds closed up again, and blacker than ever before, except perhaps during the days of the Retreat from Mons, grew the gigantic bastion of storm through which we had to pass.... Even so once, thunderclouds collected before me when I was on the top of an Alpine peak, gathering and growing thicker with extraordinary swiftness. ”

“ The speed of rise of the air beneath the base of the thunderhead is a question of some interest in aëronautics. If the ascent be so much as a foot or two per second, one may expect the vultures to prefer soaring beneath the thundercloud during its formative period. Here also the aëroplanist might attempt a record flight, if the cloud were high enough to be out of his way. ”

“ Sometimes the upper edges have the compact form of cumulus, rising into massive peaks round which the delicate false cirrus floats, and sometimes the edges themselves separate into a fringe of filaments similar to that of cirrus. This last form is particularly common in spring showers. See fig. 10.
The front of thunderclouds of wide extent frequently presents the form of a large bow spread over a portion of the sky which is uniformly brighter in colour.
10. Stratus (S.) .—A horizontal sheet of lifted fog. ”

“ The frozen particles which make up the top subside gradually, and the chilling of the air immediately below the cloud brings the saturation level nearer the ground, and we say the cloud base descends.
The arrangement of a thunder-cloud into the upper and lower discs with a connecting uprush gives to the typical cloud a shape something like that of an anvil when seen sideways, but in the larger clouds the disc-like form is more obvious. In any ordinary thunderstorm the great majority of the discharges of lightning play between the two discs, and the larger the cloud the more frequent these are. ”

“ Every time the thunder burst above their heads, he could feel her heart beat against his. One of her arms was round him; the other he held; all wet it was with the fear. He did not speak: he only clasped her closer every now and then, that she might be reminded of her shelter.
Twenty minutes, or so, and the violence of the storm abated. The lightning grew less frequent, the thunder distant and more distant. At length the sound wholly ceased, and the lightning subsided into that harmless sheet lightning which is so beautiful to look at in the far-off horizon. ”

“ The outline of a black thunder-cloud is striking, from the great energy of the color or shade of the general mass; but as a line, it is soft and indistinct, compared with the edge of the cirrus, in a clear sky with a brisk breeze. On the other hand, the edge of the bar turned away from the wind is always soft, often imperceptible, melting into the blue interstice between it and its next neighbor. Commonly the sharper one edge is, the softer is the other, and the clouds look flat, and as if they slipped over each other like the scales of a fish. ”

“ Subterranean thunders suddenly break it—thunders coming evidently from the bosom of the great mountain yonder, thunders that shake and crack and rend the very ice on which you stand, causing the bergs to grind and shriek like monsters in agony. The great cloud pall has risen higher and spread itself out, and now hangs horizontally over half the island, black and threatening, its blackness lit up ever and anon with flashes of lightning, sheet and forked, while, peal after peal, the thunder now rolls almost without intermission. ”

“ The cloud in the horizon began to extend itself, increasing and gradually rising and covering the sky, and the old man’s prediction was evidently about to be fulfilled. A dead calm lay upon the river, and a preternatural stillness clothed in a sort of stupor the whole face of nature around us; while low muttering rolls of thunder from the dark cloud, and the frequent, sudden, crinkling lightning, glittering across its surface, warned us that we were about to encounter one of those violent and terrible thunder-storms which not unfrequently occur in this part of the country. ”

“ To say that the thunder is incessant, does not adequately convey to the mind the terror of these prolonged peals which seem to originate in the horizon, roll upward to the zenith, louder and louder, until, silent for a moment, they burst upon the earth in blinding flame, and a concentrated crash, which makes the very mountains reel to their foundations. Not from one direction alone, but from every quarter of the compass, the elements seem to gather to the fierce encounter, and the thunder booms, and the lightning blazes from a hundred rifts in the inky sky. ”

“ Sometimes we have a hot, scorching gale all day, drying and parching one’s very skin up, and shriveling one’s lovely roses like the blast from a furnace: then in the afternoon a dark cloud sails suddenly up from behind the hills to the west. It is over the house before one knows it is coming: a loud clap of thunder shakes the very ground beneath one’s feet, others follow rapidly, and a thunderstorm bewilders one for some ten minutes or so. A few drops of cold rain fall to the sound of the distant thunder, now rolling away eastward, which yet “struggles and howls at fits.” ”

“ Blinding glare would show a sky of rent, fierce, tumultuous clouds in layer after layer. If only he could more easily keep his rain-blinded eyes open, to see those incredible effects of the cloud-masses when the lightning tore them apart! Such marvels of shapes and depths and unearthly colors in them! And also such tremendous gradations of sound in the rolling thunder as it reverberated from every side at once, now near, now far, crashing against the cliffs above, and tumbling its gigantic echoes back on his own head. Mad revelry of the storm-gods! ”

“ As I approached the wood, there came a flash of lightning, pale, but covering the whole visible sky, followed after a long interval by a distant roll of thunder, which lasted several seconds and ended with a succession of deep throbs. It was as if Nature herself, in supreme anguish and abandonment, had cast herself prone on the earth, and her great heart had throbbed audibly, shaking the world with its beats. No more thunder followed, but the rain was coming down heavily now in huge drops that fell straight through the gloomy, windless air. ”

“ Then the man leaped down and trod it with heavy, cautious feet. The thunder grew louder and the lightning broke through upon the great figure treading the earth.
He flung aside the shovel and dropped to his hands and knees, scraping the earth out of the grass and moss in swift handfuls and throwing it loosely on top of the hole. The lightning playing across the sky flickered on the dry grass and moss and over the great trees and bleak cliff and the figure in its clumsy garment, half cape, half coat, crawling about the hole like some huge insect surprised at its work. ”

“ A flash of vivid lightning now flared in her eyes, and left her for a moment in suspense whether she had not been blinded by the bright fluid; then on came the peal of thunder, which reverberating among the mountains like discharges of artillery, filled her [Pg 179] with that peculiar awe which the speaking clouds throw over the hearts of mortals. The rain came down in torrents, and had scarcely begun to pour, when the speat-rills of the high lands were heard dashing down like angry spirits to swell the Henderland Burn and the Megget, and raise the fury of these mountain streams. ”

“ We first noticed a small cloud gathering about the top of the mountain, which presently commenced circling around the peak, occasionally reaching over far enough to drop down upon us a few sprinkles of water, although the sun was shining brightly where we were. As the cloud continued to circle, it increased in size, momentum, and density of color, spreading out like a huge umbrella. Soon thunder could be heard, growing louder and more frequent until it became one continuous roar, fairly shaking the earth. ”

“ If the air of a warm, moist summer afternoon becomes still and oppressive and if cumulus clouds increase in size, a thunder-storm is very likely to follow; and if a nearby cumulus expands vertically into a thunder-head the storm is pretty certain to follow, somewhere or other in the vicinity. The thunder-head may be visible every where within a radius of 25 miles, but the storm path may be a narrow strip not more than 30 miles in length. The path of the thunder-storm, like that of the tornado, is determined by the circulation of the cyclone in which it is formed. ”

“ Even thunder-showers are wrested by some men into a political significance!
The circumstances of the case, however, would appear to have been these: A dense cloud, borne upon a low southwest surface-current of wind, was passing across the deep valley of the West River, half a mile or so from its mouth, when it was probably struck by a cool, dry mountain-breeze flowing down the valley. This breeze imparted new electricity to the cloud, which, being thus overcharged, gave out its surplus in a sudden shock, which took effect upon, a group of pines. ”

“ Flash succeeded flash, peal after peal of thunder, harsh, sharp, and deafening, reverberated from rock to rock. It was unlike any thunder I had ever heard before—not the deep bass roar that one listens to in a storm off the Cape, nor the crashing big-gun sound of thunder in the mountains. The noise was of a tearing, rending character, and resembled platoon or volley firing as near as anything I know of. But the effect of the lightning among the falling snow was most beautiful and wonderful. ”

“ THUNDER and Lightning are occasioned by an exhalation hot and dry; and being carried up into the middle region of the air, and there inclosed into the body of a cloud; now these two contraries being shot or inclosed, into one plate together, they fall at variance, whereby the water and fire, agree not till they have broken through, so that the fire and water fly out of the clouds; the breaking whereof makes that noise which we call thunder, and the fire is lightning which is first seen, though the thunder crack he first given, because our sight is quicker than one hearing. ”

“ How often do we hear the voice of the loud thunder rumbling and rolling away above the cloud-surface, like the echo of artillery discharged among the hills! Hence we perceive or infer that the clouds intercept the progress of sound, as well as of light and heat, and that this upper surface is often like Alpine regions, which echo back and roll along with rumbling noise the mutterings of the distant thunder. ”

“ I perceived that I had used the wrong illustration, for, of course, thunder-clouds were not known underground.
"The only trouble," proceeded my neighbor, after I had vainly tried to convey an idea of the nature of a thunder-cloud—"the only trouble is in aiming the lightnings. Of course, we try to direct them accurately through the different tubes, but they don't always go where we want them to. You can never tell where the lightning will strike." ”

“ The lightning plays around the summits of the mountains in a constant succession of brilliant flashes, whilst the thunder is prolonged through the deep ravines and distant valleys, until the echo of the one peal and the crash of another blend together in one never-ending roll. Heavy falls of snow often accompany these storms, and the condition of travelers crossing the passes during one of them is most distressing. Unable to advance or to retreat, they halt and wait, in momentary fear of being hurled over the mountain sides. ”

“ And no appearance in nature joins more powerfully the elements of grandeur and awe than a heavy thunder-storm. When, suddenly, from the breast of a dark thunder-cloud a brilliant flash of light darts zigzag to the earth, followed by a loud crackling noise which softens in the distance into weaker volumes of sound, terror seizes the birds of the air and the cattle in the field. The man who is born to rule the storm rejoices in the powerful display ”

“ It would be necessary to go to some length to explain the familiar electrical manifestations of the thunderstorm—some points, indeed, are not perfectly clear to meteorologists—but it should be stated that these are always the result, not the cause, of the storm. Lightning is an electrical discharge between cloud and earth, or cloud and cloud, and thunder is simply the violent soundwave set up by the sudden expansion of the heated air along the path of the discharge,—the same acoustic phenomenon that accompanies an ordinary explosion. ”

“ The crack of thunder suddenly wakens us from our reverie. A bank of clouds, dark underneath and contorted with churning air, is rolling over the ridges and into the head of the valley. The clouds shoot lightning toward the slopes below. Hypnotized by the spectacle we remain rooted to our rocks until the first drops fall, then we pull on our ponchos, determined to greet the storm. ”

“ Another illustration of lightning resulting from cloud agency, rather than controlling them, may be found in the cloudless Sahara, where evidences of electricity are sometimes to be observed in the time of the Khamsin, while the thunder storm is unknown. One notable exception to the rule that thunder storms are violent and frequent in all tropical regions is to be found in Peru, with its cloudless skies and eternal sun, where a rainfall or a thunder storm would be as great a curiosity as a palm tree at the north pole. ”

“ I looked all around the horizon, and could not discern a cloud that could hold a pint of water.
“Look, sir,” said the toll-gatherer, “you perceive to the eastward, just above that hill, a small black cloud not bigger than a blackberry, and while I am speaking it is doubling and trebling itself, and rolling up the turnpike steadily, as if its sole design was to deluge some object.”
“True,” said I, “I do perceive it; but what connection is there between a thunder-cloud and a man and horse?” ”