Nocturnal emission

“ Solar light, being electric, is not developed as light until reaching the atmosphere of a planet or satellite, or their more solid substance, which would explain why solar light is not diffused through space, and thus account for nocturnal darkness. ”

“ On the other hand, if the air contain transparent vapour, and the sky appear clear, the counter-radiation will be less, the earth will cool rapidly, and the deposit of dew will be copious; provided the night be comparatively calm, for, when the wind blows, the circulating air supplies heat to the radiating substances, and prevents any considerable chilling. ”

“ Everywhere the awakening came with the sunrise. We awakened to the gladness of the morning; we walked dazzled in a light that was joy. Everywhere that was so. It was always morning. It was morning because, until the direct rays of the sun touched it, the changing nitrogen of our atmosphere did not pass into its permanent phase, and the sleepers lay as they had fallen. In its intermediate state the air hung inert, incapable of producing either revival or stupefaction, no longer green, but not yet changed to the gas that now lives in us. ”

“ Though the summer days of the northern localities are warmer than their elevation would indicate, the nights are not proportionally cold; for the light mist of 14,000 feet, which replaces the dense fog of 7000 feet, effectually obstructs nocturnal radiation, though it is less an obstacle to solar radiation. ”

“ It has been proved that, in the production of this effect, the sun does not act as a body that heats. The emission of the gas is determined by the light: pure air is therefore separated by the action of light, and the operation is stronger as the light is more vivid. By this continual emission of vital air, the Almighty incessantly purifies the atmosphere, and repairs the loss of pure air occasioned by respiration, combustion, fermentation, putrefaction, and numerous other processes which have a tendency to contaminate this fluid so essential to the vigor and comfort of animal life ”

“ The great absorption and emission of light in the polar regions, by the ice and snow, may cause the extraordinary illumination of that country during the absence of the sun, and the emission of the magnetic rays with electricity may, perhaps, give us the aurora borealis. ”

“ And if they intercept and retard the passage of heat coming to the earth, they also retard radiation from the earth at night. In other words, the amount of insolation—that is, of solar heat—received at the earth’s surface is quite as variable as is the daily range; indeed, it is the highest expression of the daily range. At sea level dry air does not always indicate warm days and cool nights; but at levels of 5000 feet or more this is the rule rather than the exception. At any level, changes in temperature are more rapid in dry than in moist air, and the reason therefor is obvious. ”

“ In the night, the condensation is caused by loss of heat through radiation. Radiation shows that the air above must be dry. Therefore a gray morning means a dry air above the water drops, and this means a fine day, for the droplets will soon be evaporated by the rising sun. The red morning sky declares that the dust particles have been protected from radiation by a blanket of overlying moisture, the air, therefore, is saturated to great heights and rain is probable. So you see, Anton, Mammy's rhyme is right. ”

“ No matter how fiercely the sun might shine, life on the earth would be entirely destroyed by cold.
When water vapor, clouds, or dust motes intercept certain portions of the sun’s rays, they change them from vibrations in ether to the motions of molecules, and the motions of these molecules are expressed in a rise in temperature in the vapor, cloud, or dust. Earth radiations of heat, having longer and slower wave lengths than those that come from the sun, are more readily absorbed by the atmosphere. ”

“ When the Sun after the oppressive day sinks behind the horizon, it is well known that a sharp fall of temperature occurs, particularly in arid zones, but also in humid regions within the tropics where this very phenomenon is utilized for the production of ice. He who exposes himself to the sudden cold of the night falls an easy prey to illness. Particularly is this true under a clear sky—primitive people say “when the Moon shines”—because of the strong radiation. ”

“ Any natural process having a tendency to cool the air, so that its temperature falls to or below the dew-point, without originating any lateral motion to clear away the extraneous atmospheric impregnations which ensue, will contribute very much to concentrate them in the lower portions of the air.
Now this is the case with terrestrial radiation, which, with a clear and calm atmosphere, rapidly diminishes the temperature of certain parts of the earth's surface, and the circumambient air, condensing the vapour it contains, and creating a local, cold, damp, and very often malarious, atmosphere. ”

“ The electric state of the atmosphere has no doubt a great effect upon the constitution, though its mode of action may not be well ascertained. The moon in all countries is blamed for her evil eye, but heat and electricity must exert an equal influence, and the moon is blamed for all; predictions of the weather founded upon the phases of the moon are vague and uncertain,and I think that her effects upon public health are equally difficult to be anticipated. ”

“ There is enough air here to refract light slightly, as at twilight, and to render luminous the meteors that rush with fearful velocity against its widely scattered molecules. At this distance from the earth there probably is no more air than would be found under the receiver of the best air pump, and, the reader will be surprised to learn, darkness is practically complete, although the hour may be midday, for there are no dust motes to scatter and diffuse and render visible the light rays of the sun. ”

“ Whether the exchange of electricity is produced on a vast stretch between two rows of clouds, or whether it is manifested by a long thin spark launched like an arrow and veiled by the curtain of clouds, all that can be seen is a strange light, vague, diaphanous, instantaneous, which sometimes spreads itself like a sheet of fire all over the horizon.
It is diffused lightning which gives us the finest storm effects on those heavy summer evenings when the air is breathless and saturated with electricity. ”

“ When the flash is from one cloud to another there is sheet-lightning, which is beautiful but not dangerous; but, when the electricity passes from a cloud to the earth in a forked form, it is very dangerous indeed. The flash is instantaneous, but the sound of the thunder takes some time to travel. Roughly speaking, the sound takes five seconds or six beats of the pulse to the mile.
All are now taught at school that it is the oxygen in the air which is necessary to keep us in life. If mice are put into a glass jar of pure oxygen gas, they will at once dance with exhilarating joy. ”

“ The actuating force of every wind that blows; of every mighty current that streams through ocean depths; the motive cause of every particle of vapour in the air of every mist and cloud and raindrop, is Solar Radiation.
“The delicate tremor of the sun’s surface particles, shot hither through thirty million leagues of fine intangible æther, has power to raise whole oceans from their beds, and pour them down again upon the earth. We are apt to measure solar heat merely by the sensation it produces on our skin, and think it small and weak accordingly; a good coal fire will heat us more. ”

“ But we know little of the laws which govern atmospheric radiation, and presumably, if cloud could be produced by such means, it ought to make its appearance most frequently in the small hours of the morning before sunrise. We are, however, unaware [89] of any variety of cloud which answers those conditions, unless it be the ground fogs which so often form during the night; and these, we know, are certainly due to the chilling of the air by contact with the ground, which has been cooled by radiating away its heat. ”

“ Finally, I must mention another effect of smoke, and that is the amount of light absorbed by the smoke-cloud hanging over the city. We are not blessed with too much light at any time, especially during the winter months, and yet the smoke in some parts of the city absorbs about one-quarter of the total daylight. ”

“ More disease germs exist in river water in winter than in summer, which may be due to the greater disinfecting power of the sun’s rays during summer.
Dust Motes of the Air. As the earth pursues its course about the sun, dust rains into its atmosphere from outer space. Meteors that are burned through the heat generated by striking into our air contribute to the supply, as do volcanoes, combustion, spray from the ocean, and matter lifted up by the action of the wind. ”

“ The midnight sun is caused by certain gases igniting in the air. These gases are at rest when apart from each other, but at their joining they light up the whole parts thus occupied by them, and thus give light to all the northern parts of Europe. ”

“ The differences between the temperature of day and night are considerable; therefore all bodies expand under the influence of the higher, and contract under that of the lower temperature. During the day, any cloud obscuring the sun produces, in every solid, fluid, or aëriform body, within the range of solar influence, a check: the particles which had been expanding under the force of heat suddenly contract. Thus there must of necessity be, during the hours of sunshine, a tendency in all bodies to dilate, and during the hours of night they must be resuming their original conditions. ”

“ But about once a month they should be exposed to the full blaze of the sun for at least an hour; while a similar exposure, but of longer duration, to moon or starlight, invariably increases their power, and quite often adds new ones. ”

“ Accordingly, we see that the lighter the gas the faster sound travels in it, pressure and temperature being the same. If the atmosphere we breathe consisted of hydrogen instead of a mixture of oxygen, nitrogen, and many other gases, a clap of thunder would follow a flash of lightning much more quickly than it does in our present air, supposing the storms to be at the same distance. ”

“ When there is great heat on the land, in a particular region (the sun having shone on it perhaps several days, while the surrounding countries have been screen'd by clouds) the lower air is rarified and rises, the cooler denser air above descends; the clouds in that air meet from all sides, and join over the heated place; and if some are electrified, others not, lightning and thunder succeed, and showers fall. Hence thunder-gusts after heats, and cool air after gusts; the water and the clouds that bring it, coming from a higher and therefore a cooler region. ”

“ Q. Why is lightning more common in summer and autumn, than in spring and winter?
A. The heat of summer and autumn produces great evaporation; and the conversion of water to vapour, always develops electricity.
Q. Why does a thunder-storm generally follow very dry weather, and rarely succeeds continued wet?
A. The clouds are always charged with electricity; but dry air (being a non-conductor) , will not conduct the surplus fluid from the clouds to the earth: so it violently rends the dry air with a flash, in order to relieve the cloud, and reach the earth. ”

“ Wind blowing from a large body of water is always heavily laden with moisture, which decreases the rate of radiation both day and night, but especially during the period of cold in the early morning when frost is liable to occur. Such winds, largely affected by the temperature of the water over which they have passed, modify the temperatures of both day and night. ”

“ The problem before us is to find out the relative importance of variation of temperature and of light in the diurnal movement of the leaflets.
In the daytime the light is increasing till midday; there is, on the other hand, a rapid decline of light after 5 p.m. and uninterrupted darkness at night. As regards temperature there is a continuous rise from morning till the thermal noon at 2 p.m., after which the fall of temperature is continuous till next morning. ”

“ Often, this radiation results from heat exciting matter, vibrating its molecules.
The warmth of the planet’s surface also causes liquid water to evaporate resulting in an increase of water vapor in the atmosphere, leading to additional surface warming. ”

“ In fact winds are caused by movements between large masses of air of unequal temperature and consequently of unequal density. Light gases ascend, as familiarly illustrated by the smell of dinner perceived in bedrooms, or the smell of a cigar lit in the hall perceived in the attic. In rooms differences of temperature of the air are caused by the heat of fire, gas, and our own bodies. Currents of air result; the warmer and lighter air ascends up the chimney or towards the ceiling, while colder and denser air rushes in under the door or through the floor, etc. ”

“ In the winter similar consequences ensue, in a negative direction, from the prolonged loss of heat by radiation in the long and clear nights—an effect which is intensified wherever the surface is covered with snow, or the air little charged with vapour. ”

“ It would therefore appear that the moist atmosphere above us may, through the action of sunlight or the lightning flash as well as by other means, become ionized. The negative ions attract moisture to themselves more readily than the positive; they grow to be larger drops, and descending to the earth with their negative charges give it negative electricity, while the atmosphere is left essentially either positive or neutral. ”