Cold air

“ The air from B—"
"Do we begin all over again now?"
"More or less, yes."
"So that at this place, A, it's always raining or just going to rain?"
"Yes, if it starts by being hot there, as it did just now, I suppose it is."
"What happens if it starts by being cold?"
"It rains. I've explained that. The cold air can't contain so much moisture—"
"Don't begin that again. What about B? Is it any good going there? We had frightfully high pressure there at one time." ”

“ Did you ever on a winter’s day, when the ground was as hard as a stone, the ponds all frozen, and everything cold and still, stop for a moment, as you were running in play along the road or skating over the ice, to wonder at yourself and ask these two questions:—“Why am I so warm when all things around me, the ground, the trees, the water, and the air, are so cold? How is it that I am moving about, running, walking, jumping, when nothing else that I can see is stirring at all, except perhaps a stray bird seeking in vain for food?” ”

“ The cold had become intense, a bitter piercing cold which strained and snapped at joist and beam and turned the slush of yesterday to flint. From the street below every sound broke sharp and metallic—the clatter of sabots, the rattle of shutters or the rare sound of a human voice. The air was heavy, weighted with the black cold as with a pall. To breathe was painful, to move an effort. ”

“ But although my sense and reason inform me, that air in its own nature or essence is neither hot nor cold, yet it may become hot or cold, by hot or cold motions; for the sensitive perceptive motions of Air may pattern out heat or cold; and hence it is, that in Summer, when as heat predominates, the air is hot; and in Winter, when as cold predominates, the air is cold. But, perhaps, you will say, air may be cooled by moving it with a Fan, or such like thing which can make wind; wherefore it follows, that air must needs be naturally cold. ”

“ You know a great many times when you go out into the wind how cold it feels, and yet if the wind would actually stop, you would think it warm. It is the wind that causes the rapid evaporation and makes the surface of the skin feel cold. As it is true that the moisture in the air acts as a blanket to us in our homes, it is likewise as true that the vapor in its natural form outside of the house acts as a blanket for the earth. ”

“ The cold air descending from above, as it penetrates our warm region full of watry particles, condenses them, renders them visible, forms a cloud thick and dark, overcasting sometimes, at once, large and extensive; sometimes, when seen at a distance, small at first, gradually increasing; the cold edge, or surface of the cloud, condensing the vapours next it, which form smaller clouds that join it, increase its bulk, it descends with the wind and its acquired weight, draws nearer the earth, grows denser with continual additions of water, and discharges heavy showers. ”

“ You will then perceive, as the weather grows warmer or colder, that the air contracts itself into a narrower space in cold weather and dilates in the warm, which will be exhibited by the rising of the water as the air contracts itself, and its depression as the air dilates. The sensibility of the air with regard to heat or cold is so delicate and exquisite, that it far exceeds the human touch, so that a ray of sunshine, the heat of the breath, and much more, that of the hand placed on the top of the tube, immediately causes an evident depression of the water. ”

“ You ask me to explain why I am afraid of a draft of cool air; why I shiver more than others upon entering a cold room, and seem nauseated and repelled when the chill of evening creeps through the heat of a mild autumn day. ”

“ The heated air charged with moisture rises over the sunward hemisphere, and flows off above, on all sides, toward the night side, while from the latter cold air flows in beneath to take its place. Along the junction of the two hemispheres the clouds and moisture are condensed by the intense cold, and fall in ceaseless snowstorms. ”

“ Cold air is heavier than heated air, and until the clouds become so full of moisture as to return some of it to the earth, in the shape of rain, they float because they are lighter than the air underneath them. ”

“ Let one person go out into the cold air in winter for a few minutes, and let another sit by a warm fire; then introduce both into a room without a fire: the person from the cold will feel it warm, and the other will feel it cold. ”

“ It is in winter, however, that the greatest care is required in providing a constant supply of pure air. If we would but accustom our minds to comprehend, readily and quickly, that cold air falls and warm air rises, it would assist us in our conclusions. ”

“ The air contained inside of inhabited rooms gets warmed by the bodies and breaths of the persons living there. Then it is lighter, bulk for bulk, than the colder air outside, for warmth stretches and lightens everything. But as heavy things fall or press down to the earth more strongly than light ones, the cold air always squeezes into the room through the lower openings, and pushes the warm impure air out before it, through the upper ones. ”

“ Thus over a level plain on a clear calm night there is found a relatively thin layer of cold air near the ground, which increases in temperature up to two hundred or three hundred feet, or which may be only five or ten feet deep. ”

“ No sooner is the door opened than a shower of snow at once fills the carriage. This is simply the moisture suspended in the air and generated by human lungs. The rush of cold air at once freezes this moisture and converts it into snow, thus showing those who will condescend to learn, that they have been breathing and re-breathing the air that has passed through a variety of human lungs, and is charged with their different moistures. ”

“ This warming and cooling of the air is well illustrated by what takes place in a dwelling-house. If you pass out of a warm room, on a winter’s day, into the open air when there is no wind, you feel a sensation of cold. Whence does this sensation come? Not from anything you can see, for your feet, though resting on the frozen ground, are protected by leather, and do not yet feel the cold. It is the air which is cold, and which encircles you on all sides, and robs you of your heat; while at the same time you are giving off or radiating heat from your skin into the air. ”

“ The hot day had warmed the air close to the pavement, but the cooling of the surface at the onset of darkness had caused a layer of warm air to be sandwiched in between the cold air close to the road surface and the cold air above. ”

“ Cold air, as well as cold ground, condenses the vapor of warmer air. If you watch what goes on along the course of a river, you will often see examples of this kind of condensation. The ground on either side of the river parts with its heat after sundown sooner than the river itself does, and consequently cools the air above it more than the air above the river is cooled. ”

“ We do, in fact, see this action evidenced; when in winter time the cold condenses the vapour of the breath, we see the little cloud constantly rising before the breather's face, and dispersing in the surrounding air. ”

“ Fig. 714.—High tide and storm on the coast of Schleswig.
Heat, we know, is the effects of the rapid motion of small particles of matter, and is radiated from our bodies—so we feel cold; it reaches our bodies, and we feel warm. So air is heated or cooled by the sun, not in its absence, except when the earth and air have been so warmed during the day that the heat is given out by them long after sunset. We have read of the pressure of the atmosphere in the Physics section, and that warm air is lighter than cold air, as shown in the ascension of the Montgolfier balloon. ”

“ They are thus admirably pro tected from the extremes of cold in winter, because the descending cold air-currents are diverted aside into the ravines, and the counter-currents are constantly supplying warmer air from the higher regions of the atmosphere. ”

“ Frost, Ice, Snow and Hail, do not proceed from the coldness of the air, but rather the coldness of the air proceeds from them; for Ice, Snow, and Hail, proceed from cold contraction and condensation of a vaporous or watery substance; and, as Frost and Snow cause air to be cold, so Thunder and Lightning cause it to be hot, so long as they last. ”

“ However much you may augment the fire, the cold air becoming heated will rise, and fresh cold air will at once take its place; and therefore no equal distribution of warmth in the house will be attained. ”

“ The cold, though less severe than with us, is damp, raw and insidious, and creeps under wraps with a treacherous persistency that nothing can shut out. The ill-fitting windows, opening in the old door-like fashion, let in every breath of the chill outer air. ”

“ You can no longer imagine, as before, that it would be delicious to die of cold;—you shiver even with all the windows closed;—you feel currents of air,—imperceptible to nerves in a natural condition,—which shock like a dash of cold water, whenever doors are opened and closed ”

“ Do not, by any means, expose him suddenly to cold air, or a cold breeze, as on going into a cold room, going out into cold air, or undressing or dressing in a cold room. Uniformly warm temperature is of great importance. ”

“ Loomis suggested in a former paper that intense and sudden cold arises from vertical movement or displacement of air, by which the warm air suddenly, in some cases almost instantly, rises, the cold air of the upper atmosphere displacing it by its descent. ”

“ I answer, That doth not prove Air to be in its nature cold: for this moving or making of wind may contract or condense the air into cold motions, which may cause a cold wind, like as Ventiducts, where the air running thorow narrow Pipes makes a cold wind. The same may be done with a mans breath; for if he contract his lips close, his breath will be cold, but if he opens his mouth wide, his breath will be warm. ”

“ A. Blowing causes the air (which covers the hot food) to change more rapidly; in consequence of which, the hot air is quickly blown away, and gives place to fresh cold air.
Q. Why do ladies fan themselves in hot weather?
A. By the action of the fan, fresh particles of air are perpetually brought in contact with the face, and every fresh particle of air absorbs some heat from the skin.
Q. Does the fan cool the air?
A. No; it makes the air hotter, by imparting to it the heat out of our face: but it cools the face blown upon, by transferring its heat to the air. ”

“ The cooler air from the land is carried over the water by convection currents, flows in and under the warm air, is heated by the water and rises, to be replaced in turn by the further flow of cold air from the land. ”

“ Q. Why does wind in England generally feel cold?
A. Because a constantly changing surface comes in contact with our body, to draw off its heat.
Q. Why is a room (even without a fire) generally warmer than the open air?
A. As the air in a room is not subject to much change, it soon becomes of the same temperature as our skin, and no longer feels cold.
Q. Why do we generally feel colder out-of-doors?
A. Because the air (which surrounds us) is always changing; and as fast as one portion of air has become warmer by contact with our body, another colder portion surrounds us to absorb more heat. ”

“ There is another reason why, on clear nights at least, the cold is more severe in low confined places that are sheltered from the wind. The radiation of heat into the sky, which I lately explained to you, reduces their temperature below that of the air, except what is in immediate contact with them ”

“ It is this that makes our sky be cloudy or clear; that produces rain and sunshine, snow and hail, refreshing coolness in summer and warmth sometimes in midwinter, as also chilly nights in summer and thaw in winter. In other words, it is more properly the motion of the air, the wind, that produces what we call weather; that is, that changeableness from heat to cold, from dryness to moisture, all of which may be comprised in one name, weather. ”

“ And thus, in a sudden change of the air from cold to warm, the instrument remaining longer cold may condense and absorb more moisture, and mark the air as having become more humid than it is in reality, and the contrary in a change from warm to cold. ”

“ After air, we consider those bodies to be most sensible of heat, which have been recently changed and contracted by cold, as snow and ice; for they begin to be dissolved and melt with the first mild weather. ”

“ If the external air is of a high temperature, it does not take up the superfluous heat of the body fast enough, and we complain of too much heat; if it is very cold, it absorbs the heat too fast, and produces the sensation of cold. ”

“ As our dry air is surrounded on both sides by moist air, it is evident that we must more or less partake of both heat and cold; but it moreover accounts for the happy circumstance that we have much rain ”

“ I believe this may be true, in a climate like Europe, where cold invigorates the body, and enables it to resist the effects of foul air; but I am persuaded it is otherwise in tropical climates. The external heat of the air induces great languor and relaxation, and we cannot breathe the same portion of air for the same length of time in a hot as in a cold climate, without great uneasiness. ”

“ This suppression is, as I have said, occasioned by the cold winds, which fall from the air, bind the earth, freeze the waters, and shut up the emanations of the terrestrial heat during the time the frosts remain; so that it is not at all surprising that the cold in winter is in fact so much the greater as we advance further towards the climates where the mass of air, receiving the rays [321] of the sun more obliquely is for that reason colder. ”