James Mackintosh

“ Since air in expanding under pressure produces work, and since heat is an equivalent of work, it expends heat in so doing, and is thus lowered in temperature. Consequently, the ascending air rapidly cools as it rises. Now, this air is carrying large quantities of vapor of water with it, which likewise is cooled by expansion. But you cannot cool vapor at any tension below a certain temperature without condensing it; and so, indeed, it happens. The steam carried up by the cyclone is condensed into rain, snow, or hail, and falls to the earth. ”

“ It was literally an atmosphere, and nothing else. All the matter of the earth then floated, a vast globular ocean of vapor. The power which kept its particles apart was heat. Before these particles could come together and the solid foundations of the world be laid, it was necessary that the heat should be got rid of. The means by which this purpose was accomplished was mainly the cyclone. Around the limits of the vaporous world radiation into empty space could go on rapidly. Not so in the interior. Conduction of heat even along a bar of iron is a very slow process. ”

“ In condensing it gives forth the enormous quantity of insensible heat which it received from the sun. This heat is imparted to the ascending current, and thus keeps it warmer and therefore specifically lighter than the strata through which it is rising. The heat of the sun, which had been potential in the vapor, is converted into the energy developed by the cyclone.
We thus see that the cyclone is really a kind of vast steam-engine. On our earth its furnace is the sun, and its boiler the moist lands, the rivers, lakes, and oceans. ”

“ While these practical results are exceedingly worthy of attention, and inspire us with the hope that the time shall come when perfected instruments, improved methods, and increased knowledge, shall enable the meteorologist to predict with the utmost certainty every atmospheric disturbance, they yet fall into the shade when compared with the magnificent and luminous conceptions which meteorology has added to cosmological science. ”

“ As soon, however, as the diminution of specific gravity due to higher temperature is greater than that due to diminished pressure, the lower stratum will break itself a way through the air above it, and rush up through the opening. This result may be attained, and is generally reached, by favoring circumstances, long before equilibrium is totally destroyed. When once the' heated air has thus at a particular point formed itself a channel of escape, the warm stratum along the surface of the earth rushes toward the opening, and there ascends, while the colder air above descends to take its place. ”

“ In the sun itself it is a portion of the primeval stock of heat which is removed.
The cyclone may therefore be defined as the universal cooler of creation. There is not a sun which lights the midnight sky, or which the telescope has brought within mortal ken, which is not vastly indebted to the cyclone. Though so simple as easily to be understood by a child, it is a powerful means by which the Almighty-works. It is a key to very many of the secrets of the universe. ”

“ We have thus presented to our imaginations a Vast cyclonic column thousands of millions of miles in height, up which vapors of great variety, and collected at very various altitudes, are rushing with terrific force, and condensing as they go. ”

“ Moreover, since the strata would be, in the main, according to their specific gravity, and since some of the gases would evaporate and condense at different temperatures from others, showers of different kinds of metals and stones would tend to form at different altitudes. This would be counteracted, at least in part, by the tendency of the cyclone to reach clear up from the lowest depths to the circumference. That the disturbances in our own atmosphere extend to an immensely greater height than is generally supposed, and probably almost to the extreme limit of the atmosphere, is now certain. ”

“ This gives the general idea of the cyclone for all space and time, but not the sources of its power. These are to be found in the less specific gravity, potential or actual, of the lower atmospheric strata as compared with that of the higher. Air, and gases generally, expand when heated, and become specifically lighter. It thus tends to rise above the superincumbent colder air. (We see this illustrated in our chimneys every day.) If the air over the surface of a plain becomes heated by contact with it, its specific levity is increased, and it tends to rise. ”

“ It is million-fold slower through gas. Hence, the quickest way of carrying the heat from the interior to the summit of the atmosphere, where it might escape, was, to carry up the matter itself which contained a large amount of heat, either actual or potential. This work was accomplished by the cyclone. ”

“ Accordingly, the great majority of civilized countries, including China, the oldest of them, have already established weather bureaus, whose business it is to forewarn the mariner of coming tempests, and to give us all a timely notice when we shall require an umbrella or a great-coat. ”