Mean temperature

“ In the western division, or great plains, severe heat is experienced throughout the summer, and on occasional days the thermometer in the shade ranges above 100° Fahrenheit, but it is a dry heat and more easily borne than a much less degree of temperature at the sea-board. The mean summer temperature ranges between 75° at Deniliquin in the south and 84° at Bourke. ”

“ In different countries different patterns of thermometer shelter are employed and exposure takes place at a different height above the ground. Results so obtained cannot be critically compared, and the relative mean temperatures of the atmosphere in different countries are only known to within one or two degrees. ”

“ On the other hand, radiant heat passes easily through the air, strikes the thermometer, and raises its temperature quite independently of the influence of the air whose temperature we wish to measure. ”

“ This equalization of temperature, moreover, takes place much more rapidly, than it would do in a solid body; hence alternations of heat and cold, as day and night, summer and winter, produce in water, inequalities of temperature much smaller than those which occur in a solid body. ”

“ 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. ”

“ When the air has passed over cold countries, it will probably arrive here at a temperature much below our own, and then it must absorb heat from every object it meets with, which will produce a general fall of temperature. ”

“ The temperature of man is about 98°, (Fahrenheit’s thermometer,) and that of some other animals is higher; the temperature of birds, for example, is about 110°. It is obvious, that in most parts of the globe, the heat of the atmosphere is, even in summer, less than that of the human body. In our latitude, the mercury rarely attains 98°, and sometimes it descends to several degrees below zero. ”

“ 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. ”

“ 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. ”

“ Going out into the open air, in the temperate, and warm 324 months of the year, we often meet with bodies of warm air, which passing by us in two or three seconds, do not afford time to the most sensible thermometer to seize their temperature. Judging from my feelings only, I think they approach the ordinary heat of the human body. ”

“ Our great luminary emits an incessant flood of radiant heat in all directions. A minute fraction of that heat is intercepted by our earth, and is, directly or indirectly, the source of all life, and of nearly all movement, on our earth. To pour forth heat as the sun does, it is necessary that his temperature [Pg 516] be enormously high. And there are some facts which permit us to form an estimate of what that temperature must actually be. ”

“ Our sense of comfort in hot weather depends on the sensible temperatures. These sensible temperatures are not the same as the readings of the ordinary (dry-bulb) thermometer, because our sensation of heat or cold depends very largely on the amount of evaporation from the surface of the body, and the temperature of evaporation is obtained by means of the wet-bulb thermometer. Wet-bulb readings at the various stations of the Weather Bureau are entered on30 all our daily weather maps. ”

“ The unit of temperature is a degree, a measured part of the expansion which a column of mercury within a tube undergoes when heated from the melting point of ice to the boiling point of water at sea level. ”

“ For mental activity the temperature is much lower than for physical, being an average of approximately 40°. In other words, people’s minds are most alert and inventive when the temperature falls to about freezing at night and rises to 45° or 50° by day.”—Huntington and Cushing’s Human Geography. ”

“ 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. ”

“ It will, no doubt, be urged that a house kept up to 50° and 55° makes people "delicate;" that they "catch cold" when they go out; that a hardening process is healthy, and so on.
Our reply is, that a uniform temperature of 50° and 55° is natural and healthy. ”

“ Any one who shows over ninety-nine degrees Fahrenheit is examined further for corroborative symptoms. The temperature of every one of the steerage is taken and the glass thermometer is not always cleaned as it is passed from mouth to mouth here in these crowded regions! ”

“ Upon touching my side, it felt cold like a corpse; and yet the actual heat of my body, tried under my tongue, and by applying closely the thermometer to my skin, was 98 deg., about a degree higher than its ordinary temperature. When the heat of the air began to approach the highest degree which the apparatus was capable of producing, our bodies in the room prevented it from rising any higher ”

“ At times in midwinter the thermometer registers much below zero. These days of low temperature invariably follow a fall of snow, and before the bright sunshine that is sure to come has tempered the dry, cutting atmosphere. ”

“ 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. ”

“ The general expression of the passage of heat through every element of the surface of a body of which the temperature varies, is composed of one factor relative both to the state of that surface and to the material of the body, multiplied by the difference of two similar functions, one of which depends on the variable temperature of the body, the other on the fixed temperature of the sphere, which are the same for all bodies ”

“ It requires as much heat to convert these solids into fluids, without at all increasing their temperature, as it does to raise the temperature of water from the freezing point, one hundred and forty degrees, or from thirty-two to one hundred and seventy-two degrees, as indicated by the thermometer. This principle is of vast importance to the world, and particularly to the inhabitants of cold countries, where the ground is covered with snow and ice a part or the whole of the year. ”

“ Observation shows that when the quantity of vapour in the air is great, and also when the relative humidity is high, temperature falls little during the night, even though the sky be perfectly clear ; but when the quantity of vapour is small, or the relative humidity is low, temperature rapidly falls. On the other hand, during the day the temperature rises slowly, when the quantity of vapour is great, or relative humidity high, even though the sky be clear, but when the quantity of vapour is small, and humidity low, temperature rapidly rises. ”

“ When air holds all the moisture it can sustain, its moisture is said to be at 100 per cent.; when it holds only one-half as much as its temperature demands, it is said to be at 50 per cent.; and when it holds three-fourths of what its temperature requires, it is at 75 per cent. ”

“ The interior temperature to which the earth is subjected arises from three different sources, namely, from sidereal heat, from atmospherical heat, acting either by radiation or by contact, and from solar heat. ”

“ The temperature of the whole body is lowered, but not to the freezing point. The diminution of heat, as you know, produces a contraction in the bulk of fluids, as well as of solids. This effect, however, does not take place in water below the temperature of 40 degrees, which is 8 degrees above the freezing point. ”

“ Thus, as summer advances, the approach of the sun to a vertical position tends to produce a constant increase of temperature; but with this effect of a constant cause, there are blended the effects of many variable causes, winds, clouds, evaporation, electric agencies and the like, so that the temperature of any given day depends in part on these fleeting causes, and only in part on the constant cause. ”

“ We are always valuing the soul's temperature by the thermometer of public deed or word. Yet the great sun himself, when he pours his noonday beams upon some vast hyaline boulder, rent from the eternal ice-quarries, and floating toward the tropics, never warms it a fraction above the thirty-two degrees of Fahrenheit that marked the moment when the first drop trickled down its side. ”

“ 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. ”

“ Every substance radiates its heat, and receives in return a portion of that emitted from surrounding bodies. If two bodies of unequal temperature be placed near each other, the warmer of the two will radiate a portion of its heat to the colder, and will receive some of the heat of the latter in return; but as the warmer body will emit more heat than it will receive, the result will be, that after a time, the length of which will depend on the nature of the bodies, both will acquire the same temperature. ”

“ When the air temperature ceases to rise or fall, and begins to change at the same rate in the opposite direction, the thermometer will fail to record the true maximum or minimum temperature by an appreciable error depending upon the rapidity of the change, and will follow the new temperature changes with the same lag. ”

“ As respects the first, it has been discovered that, when underground temperatures are examined, so that local and temporary causes of change are eliminated, there is a recognizable diminution of temperature in years when spots are most frequent. ”

“ 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. ”

“ 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. ”

“ Study carefully, as in the previous problems, the relation of the different types of temperature distribution in the atmosphere to the weather conditions as shown on the daily weather maps.
Observations made in different parts of the world, on mountains and in balloons, have shown that on the average the temperature decreases from the earth’s surface upwards at the rate of about 1° in 300 feet of ascent. The rate of vertical decrease of temperature is known in meteorology as the vertical temperature gradient. ”

“ Any other temperatures may be easily determined. Suppose B C (Fig. 2) be the isotherm corresponding to the temperature of boiling water, A D that corresponding to that of melting ice, and m n an isotherm corresponding to some intermediate temperature, that marked 100° on the Fahrenheit scale, for instance, whose temperature t' upon the absolute scale we wish to determine. ”

“ As regards the mere endurance of a high temperature, the well-known experiments of Blagden, Sir Joseph Banks, and others have shown that the human body can endure for short periods a temperature of 260° F., and upwards. My own experience of furnace-work, and of Turkish baths,200 quite satisfies me that I could do a fair day’s work of six or eight hours in a temperature of 130° F., provided I were free from the encumbrances of clothing, and had access to abundance of tepid water. ”

“ The temperature of the climate is highly favorable, the thermometer averaging, during the summer season, from 76° to 79° and 80°, and rarely falling below 54°. That great enemy to grapes, rain, is not much to be dreaded ”

“ 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. ”

“ It should not he forgotten, in connexion with this subject, that though these changes are sudden, and the fall of the thermometer very great, the lowest limit is seldom below sixty degrees, somewhere about summer heat in England—a temperature most conducive to health, and one in which the animal heat is easily supported and the nervous energy suffers no depression; that the heat, though great during the hot winds, is totally unaccompanied by moisture, and that it does not continue long enough to relax the frame. ”