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Show 210 MOUNTAIN MISTS. pices) that lie bleaching in the desert, but too truly and emphatically proclaim. But though the clouds which form there produce effects so disastrous and fatal, it is probable that they could not find their way down through the mass of atmosphere that lies between that elevation and a low plain ; but they show that the atmosphere can act as powerfully at those heights as in any other situation, more so indeed than upon the surface of a level country, and more especially of a country covered with trees or other tall vegetation. There is a resistance to the wind by friction, as it passes over these ; but the swell of the air comes full and uninterrupted upon the mountain, and as those temporales prove, the loss of weight may be more than made up by increase of velocity. There is also little doubt that the mountain draws the atmosphere and the atmospheric moisture towards it, notwithstanding that it is cold, and that the general motion of the air on the surface is towards the warm place. Over white snow, the air when the sun shines is warm,-very warm as compared with that over a vast and black surface at a much smaller elevation. Of course the air ascends in consequence ; and the very snow on the mountain has a self-maintaining property, though it is continually refreshing the lower places with springs and streams. But though the atmosphere over high mountains. warmed as it is by the heat reflected from the snow raises moisture higher than the atmosphere does over plains, yet it is less able, in cases of change of temperature, to sustain t~at moisture. If the mo~ntain is so high that the au has only half the dens1ty that it has at the mean level of the earth, then the same volume of it will support only half the weight, whether of cloud or of any thing else. Thus the very same texture of cloud which is. a !og over the city, or a creeping and even a dry m1st 1n the vallev. CURL-CLOUD. 211 may be a very wetting rain on the mountain Eve one must kno.w the saying that " a Scotch ~ist wdt wet an Englishman to the skin;" and the fact is corr~ct, both as to Scotch and to all other mists ~r?vided they be mountain mists, and at a sufficient ~~~ght .. -A ~tranger, when he sees a light white rm:st trallmg m detache? parts, among the era s and hoUows of the mountam above him lighter gto 11 appearance than the liO'htest "se~-rack" h.a h piJ.~ys by,~he b~ach on a May morning, so dry ~a~cit WIU not dew on a cobweb, heeds it no more than h~ wo.uld heed that. But when he enters it he finds his m1stake. The drops are no doubt much smaller than those of " lowland" mists ; but they are three to one at the least, and they do not hit and dash off by means of the force 'Vith which they strike as !he l~rge drops do. They all adhere · and whe~ it J.S qmte calm, as it often is when they are falling and when the cloud just obscures but does not hid~ the sun, the stranger has a chance of being " wet throl:lg~," b_e~ore common notice has made him sure that It 1s rammg. The minuten~ss of the dro 8 not only aUows.the solar light to come dimly throu~h the c!oud, but It_ ca~ses that cloud to look white at a dlstanc~, ~hrch mcreases the deception. Nor ts It only when they form around mountains !hat theEJe ~levated clouds produce rain, or lead to rts produch?n, for they have similar effects when they form m the atmosphere. The " curl-cloud" which appears ~treaky in the uppermost part of the sky, and the cucle of vapour which is often seen round the moon, are much more certain indications of bad weather than much denser clouds that lie lower. A ?loud· that just floats is as ready to fall at :~y ?n~ hetght as at ~my other; but the higher up at It IS the ~ess action puts it into motion downward. The higher cloud thus, as it were commands ~;hole atmospheric action ; and thodgh the heat ought of the earth and lower part of the atmo- |