Absolute temperature

“ There would be extremely little heat to disturb the atmosphere with motion, for the dry gases of the atmosphere are practically diathermanous, and the heat of the sun would pass out by radiation from the burnt and parched surface of the earth during daytime without imparting more than a minute fraction of its energy to the atmosphere; and at night the thin surface of the top soil that had been heated to a furnace temperature during sunshine would be quickly locked in the fastnesses of intense cold—probably 200° below zero. ”

“ I am aware moisture in the air makes a great difference as affecting the human system; but a fact is a fact. The cold air from the same direction—equally charged with aqueous matter at different times—shows a difference of ten to twenty degrees in the thermometer; and yet the air at the lowest temperature affects the human system less than the highest.
"December 20th, 5.30 a.m.—Thermometer — 5°, barometer 30.200. Wind very light, N.W. Yet there must be a storm prevailing not far from us, as a tremendous roar of waters and cracking of ice comes from the direction of Davis's Straits. ”

“ If a dry atmosphere is of uniform temperature and pressure at various levels, but has a vertical temperature gradient a little greater than the normal cooling of an ascending gas, a portion of air started upward in any casual way becomes warmer than its lateral environment, and hence continues to rise until the unstable condition due to abnormal temperature gradient ceases. ”

“ The natural temperature of the human body is 98·4°F. and the little arrow on the thermometer indicates this normal degree of heat, so that when the index rests at the arrow, the natural temperature is proved to be present. ”

“ The mean temperature for the whole year is 84° of Fahrenheit's thermometer. It is not so much the heat of any one day, though that is often great, as the want of cool nights and bracing winters, the unbroken continuousness of the heat, that enfeebles them. ”

“ When the air is dry evaporation is very rapid, but as it becomes more and more filled with moisture the evaporation is checked to the same degree. This fact accounts for the difference of bodily comfort that we experience at different times in the year when the temperature is the same. Sometimes we are very uncomfortable although [Pg 63] the temperature is not above 75 degrees Fahrenheit, more so even than we are at other times when the temperature is ten or fifteen degrees higher. ”

“ If the earth conducted heat more rapidly than it does, the inequalities of temperature would be more quickly balanced, and the temperature of the ground (below the reach of annual and diurnal variations) would differ less than it does. If the surface radiated more rapidly than it does, the flow of heat from the polar regions would increase, and the temperature of the interior of the globe would find a lower level ”

“ When the sun’s warmth converts these to vapor the absorbed heat becomes latent heat, and no longer appears as sensible heat. This fact furnishes another reason why the air over desert regions, as well as the ground surface itself, becomes heated to a higher degree. [5]
Conditions of temperature exercise a great control, not only over civilization, but over the distribution of life itself. Humanity may overcome its environment so far as temperature is concerned—man can command fire, food, and fuel to be brought to him; but other forms of life cannot rise superior to conditions of temperature. ”

“ The heat received from the sun does not penetrate far into the earth’s crust, and consequently the diurnal and even the seasonal changes of the temperature at the surface produce less and less effect with every increase of the depth. All such variations of temperature are confined to within 100 feet of the surface. At the depth of about 100 feet a fixed temperature of 52° Fahrenheit is reached, and this is true all over the earth. ”

“ The greater this difference of temperature the greater the rapidity of cooling. Careful measurements made by Tait, the English physicist, show that our earth loses every year from each square foot of surface, an amount of heat that would be able to raise the temperature of one pound of water from the melting point of ice to the boiling point of water, or from 32° F. to 212° F. The rate of loss of heat, must, therefore, have been much greater when the earth was more highly heated than it is now, and will be much smaller than now many years from the present. ”

“ It is difficult to form any numerical statement of the actual temperature of the sun. The intensity of that temperature vastly transcends the greatest artificial heat, and any attempt to clothe such estimates in figures is necessarily very precarious. But assuming the greatest artificial temperature to be about 4,000° Fahr., we shall probably be well within the truth if we state the effective temperature of the sun to be about 14,000° Fahr. ”

“ Heat Due to the Condensation of Atmospheric Vapour.—Another cause which tends to keep up a uniform high temperature in the equatorial, as compared with the variable temperatures of the extra-tropical zones, is the large amount of heat liberated during the condensation of the aqueous vapour of the atmosphere in the form of rain and dew. ”

“ This heat is relative, and though it be imparted to air far below the freezing-point, raising its temperature only a few degrees, its expansive power for that change is as great when those few degrees are low down as it is when they are high up on the scale. If such condensation of vapour do take place, then liberation of heat and expansion of air must follow, and consequently the oblateness of the atmospherical covering of our planet will be altered ”

“ Nevertheless, they are held together by a powerful force. Thus, the heat used in converting one pound of water at 212° F to a vapor at 212° F would raise 967 pounds of water one degree in temperature. Measured thus, in terms of heat units, great power is required to overcome molecular attraction. ”

“ If one were to set down the temperature of each day, add the numbers at the end of the year, and divide the sum by 365 the quotient would equal the temperature [181] always found at that place at a depth of about thirty feet. The temperature of a deep-flowing spring is always about the mean annual air temperature of the place. Here is health-giving coolness for summer and warmth for winter of which one takes little heed and derives practically no profit. ”

“ The most probable value of the effective temperature of the sun's radiating surface is 6000° Centigrade, and the minimum value for the center is perhaps five million degrees. In view of these high temperatures, and the low average density of the sun, the interior must be largely gaseous, and perhaps entirely so; although, under the stupendous pressures, a great central core is probably of a viscous consistency, but ready to assume the usual properties of a gas when the convection currents carry the viscous masses up into regions of lower pressure. ”

“ No feats of discovery, not even the search for the North Pole or Stanley's expeditions in the heart of Africa, present more points of fascinating interest than the attempts now being made by scientists to explore the extreme limits of temperature. We live in a very narrow zone in what may be called the great world of heat. The cut on the opposite page represents an imaginary thermometer showing a few of the important temperature points between the depths of the coldest cold and the heights of the hottest heat—a stretch of some 10,461 degrees. ”

“ Molecular structure affects temperature change Heat measurement units, as we have seen, are defined in terms of a temperature change brought about by heating. But the same amount of heat applied to different materials does not necessarily bring about the same temperature change—it is well known that some materials can be heated or cooled more quickly than others. ”

“ Air may be brought below the normal temperature due the height at which it may be, by radiation and other processes. It may also be raised above that normal temperature by the setting free there of the latent heat of vapour or by the action of the solar ray upon the cloud stratum. ”

“ A reflecting body, heated or cooled in the interior of such an enclosure, will acquire the surrounding temperature more slowly than would a non-reflector, and will less affect another body placed at a little distance, but will not affect the final equality of temperature. Apparent radiation of cold, as from a block of ice to a thermometer placed near it, is due to the fact that the thermometer being at a higher temperature sends more heat to the ice than it received back from it. ”

“ In fact, its effects would be so vast, that it seems hardly credible that the present loss of heat from the earth should be so great as to amount to an abatement of one-thousandth of a degree per annum, for that would mean, that in a thousand years the earth's temperature would decline by one degree, and in a million years the decline would amount to a thousand degrees. ”

“ It is equally true that, in both cases, the facts may be consistent with such an irregular distribution of the atmosphere in successive layers, or strata, of very unequal temperature as was apparent in most of Mr. Glaisher’s balloon ascents. What is completely proved is that it is only under exceptional conditions that the hypothesis of an uniform rate of decrement of temperature, directly proportional to height above the sea-level, is approximately correct for observations in the temperate zone, where there is a considerable diurnal and annual range of the thermometer. ”

“ We need not consider the formula that we have just given as applicable to very great changes in the volume of gases. We have regarded the elevation of temperature as being in inverse ratio to the specific heat; which tacitly supposes the specific heat to be constant at all temperatures. Great changes of volume lead to great changes of temperature in the gas, and nothing proves the constancy of specific heat at different temperatures, especially at temperatures widely separated. ”

“ To those whose constitution has been hereditarily adapted to a temperate or cold climate, the enfeebling effect of hot countries depends much more on the constant continuance of a high temperature than on its amount. A place with a mean temperature of 80° Fahr., which varies little above or below that point, is far more injurious to a European than one where intervals of great heat alternate with periods of cooler weather. Still more important, perhaps, is the effect of a hot climate in places where the air is habitually nearly saturated with aqueous vapour. ”

“ Quantitative measurements in temperature, based upon the calorie, have a definite place in physics; and those based on the British thermal unit have a broad application in various economies. Human sensitiveness to heat does not pertain to quantity but to intensity. A large block of ice at 30° may contain more heat, quantitatively considered, than a red-hot horseshoe. If carried into a room whose air was far below freezing, the ice might warm the room to a greater degree than would the horse-shoe. ”

“ With an average temperature of seventy-two degrees it has no extremes of heat and cold, and the thermometer seldom varies more than twenty to twenty-five degrees during the entire year. In the so-called winter season the mercury rarely goes below sixty-five degrees and the summer heat does not usually exceed eighty-five degrees. ”

“ Rise of temperature, expansion, liquefaction, evaporation. The first indication of the presence of heat is discovered by an elevation in temperature. Though man is not a reliable thermometer, he would be able, ordinarily, even if blind, to chronicle the progress of the sun, from horizon to horizon, by the increasing and decreasing warmth. The little thermometer placed beneath the tongue of the invalid gives reliable report of the combustion going on within his system. We see a thousand illustrations of the expansive effects of heat, many of which are familiar to all. ”

“ This can be measured graphically without any knowledge of the law of variation of the surface temperature, or of the laws of propagation of heat waves. The quantity of heat absorbed by the stratum (x′ x′′) in the interval considered can also be expressed in terms of the calorimetric conductivity k. The heat transmitted through the plane x is equal per unit area of surface to the product of k by the mean temperature gradient (dθ/dx) and the interval of time, T−T′. The mean temperature gradient is found by plotting the curves for each day from the daily observations. ”