The new air world

by Willis L. Moore

Man Soon Adjusts Himself to Changes in Altitude. In Colonial days it was noted that horses coming down from the mountains in North Carolina ran swifter in the races the first day or two after changing to a lower level. In going to a higher altitude an increase in the number of red corpuscles in the blood enables it to absorb oxygen more readily, and thus compensate for the loss in the density of the air. Because of this gain in the chemical activities of the life current, one feels a marked increase in strength on coming to a lower level, but the gain lasts for only a short time before there is a readjustment to former conditions. Persons with weak hearts may not be able to live at an altitude of four thousand feet, and most people experience inconvenience, at least, on first reaching ten thousand feet; but nature is accommodating, and a number of large cities prosper at altitudes of from one to two miles.

CHAPTER XI
HOW CLIMATE IS MODIFIED AND CONTROLLED

If the surface of the earth were all land, and the axis of the earth’s rotation were perpendicular to the plane of the earth’s orbit, the day and the night would be equal everywhere, and there would be no seasons. There would be no wind, for the friction of the air against the rotating earth would soon cause all levels of the atmosphere to take up the exact easterly velocity of the solid body below. The atmosphere would be contracted by cold and drawn downward so as to have less depth at the poles than at any place having latitude, and it would be deepest at the equator, where the direct rays of the sun would expand it to an altitude of probably twice what it could have at the poles. Centrifugal force—the force that causes mud to fly off the rim of a swiftly rotating wagon wheel—would further lower the height of the atmosphere at the poles and cause it still more to extend outward at the equator. The atmosphere would soon adjust itself to these constant conditions and forces and thereafter remain at rest relative to the earth. There would be no life, for there would be no vaporous atmosphere if the surface all were without water. 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.

If we now incline the axis of our imaginary earth 23½°, we shall introduce seasons whose only change, the one from the other, will be in the duration of sunlight, as there is no water vapor to absorb and utilize the sun’s rays in the initiation of motion and the creation of storms. We are assuming that there would be enough heat absorbed to prevent the atmosphere from liquefying, which it would do at any temperature lower than 312° below zero. If the temperature were to fall below the liquefying point of air, we would have the singular phenomenon of the air expanding to a gas during daylight and condensing to a liquid during nighttime, and, of course, that would mean motion and winds, but of such a nature that one would hardly dare speculate as to their peculiarities.

We introduce these hypothetical cases for the purpose of conveying a clearer idea of the overlapping of conditions and the combinations of forces that influence and control the seasons, the climate, and the weather of the earth.

If the surface of the earth were all water and its axis perpendicular to the plane of its orbit, the day and the night would everywhere be equal and there would be no seasons. With a water surface there would be an atmosphere nearly if not quite saturated with vapor of water, in other words, of practically one hundred per cent. relative humidity. It is doubtful if either animal or vegetable life could exist; the first would die of internal heat, because a saturated air would permit of no cooling by evaporation from the pores of the skin, or from the tongue and mouth of animals that do not perspire; and the second could not grow without the chemical action of sunshine, which is a necessary part of the laboratory of the leaf of every growing plant, the sunshine acting upon the green granular matter which constitutes the chlorophyll of the plant. There would be little difference between the temperature of day and of night—probably not more than one degree. As the earth would everywhere and at all times be covered with a deep stratum of cloud there would be little loss of heat to space by radiation and the temperature would be excessive, rising in the tropics to near the boiling point. We will assume that the atmosphere would reach a stable and unchanged condition of great heat and humidity and be without motion or precipitation.

If now we incline the axis of this water-covered earth and introduce the complication of seasons, we shall not only have variation in the hours of sunshine, increasing as we go from the equator toward the poles, but, the capacity of air for moisture being less and less with falling temperature, we shall have downpours of rain as the summer slowly merges into fall and the latter into winter. Although the air will be saturated, there probably will be no rainfall from the time when the temperature begins to rise after midwinter until it reaches and passes the maximum heat of summer. It is fair to assume that during the rainy period there will be cyclonic storms with torrential precipitation, and that the anti-cyclones that are a necessary concomitant of cyclones, while they may cause a temporary cessation of precipitation in the area that they cover, by the dynamic heating of the air in their downward motions, will be ineffective in fully clearing away the clouds from a water-covered earth. It is doubtful if such an earth would be suitable for life,—certainly not for man.

The Real Earth of Land, Water, and Inclined Axis. The different manner in which land and water surfaces absorb, radiate, and reflect the heat from the sun has a profound influence on climate, which also is modified by latitude, elevation above sea level, elevation above a valley or above a surrounding plane, direction of wind, height and trend of direction of hills and mountains, the position of lakes and inland seas, the relative position and magnitude of continents and oceans, storm tracks, and ocean currents.

Influence of Continents and Oceans on Climate. [Charts 1] and [2] (pages 99 and 100), constructed from observations taken on ships and on land, for a long series of years, show certain Highs and Lows of vast extent, sometimes called “Centers of Action”, because they do not travel across continents and oceans, as do the migrating Highs and Lows that cause weather. Rather do they slowly reverse their relative positions between winter and summer. Continents cool by radiation in winter more rapidly than do oceans; the air contracts, settles down and grows denser and air flows in at the top from the oceans and outward at the surface of the earth toward the oceans; thus is built up the winter Highs, or centers of action, on continents. Continents heat up by absorption in summer more rapidly than do oceans; the air expands, rises, and flows away in the upper levels to oceans and flows in at the bottom from the oceans; and thus are the Lows, or centers of action, established on continents in summer. It is apparent that these processes must be reversed for the oceans, and that the Highs will be found there in the summer and the Lows in the winter. Carefully follow the illustrations of these principles by examining the whole region north of the equator on [Charts 1] and [2].