Victor L. Conrad

“ When in summer a cool current is moving southward, it encounters the warm equatorial or tropical current, which again glides upward and over it, and forms horizontal bands of stratus clouds along the upper line of contact, as in winter storms; but, in addition, the denser cold air from the north, moving with more momentum, will lift up the warm and saturated air from the tropics, and its moisture will be condensed into masses of cumulus clouds banked up against the top of the cold current, and arranged over the horizontal stratus clouds. ”

“ When in the development of a summer storm, as above described, the two conflicting currents attain a state of equal power or resistance, and thus balance each other, which is indicated when the dense cumulus clouds over the plane of conflict become stationary, then the storm is at its crisis. The air within the region of conflict is compressed and very sultry, and this condition is always felt before a tornado by persons within its area. ”

“ As storms are produced by the movements and conflicts of warm and cold currents of air, the formation of clouds always indicates to the observer the region in the atmosphere where such movements are taking place, which would otherwise be invisible. Clouds, therefore, are the invariable precursors of storms, and the kind of clouds formed will indicate the kind of storm or atmospheric movements which produce them. ”

“ Atmospheric Currents.—All storms owe their origin to the heat of the sun, which produces differences of temperature in different portions of the earth, and thereby causes all the movements and currents which take place in the atmosphere around the globe. ”

“ If, now, the wind from the south, which has prevailed and driven back the northern current, continues in the same direction until the entire atmospheric area of the storm passes over the zenith northward, and the sky clears up from the south or southwest, as is generally the case in early autumn or late spring, then the next storm or change of weather will come from the north. ”

“ It is produced by the obliquely upward movement of the tropical current over the polar current, and by its rising more or less vertically in the vicinity of contact, after its horizontal progress northward has been checked by encountering the polar current. This oblique and upward movement of the tropical current diminishes the atmospheric pressure there, as shown by the barometer, and produces that depressing calm which is always felt by persons in any locality where this meeting of currents takes place, or over which its area moves or oscillates during the continuance of a storm. ”

“ Clouds the Precursors of Storms.—Whenever a warm current of air, saturated with moisture, meets or mingles with a cold current, the invisible moisture of the warm air is condensed into visible vapor or clouds. ”

“ This is explained by the fact that in such storms the plane of meeting of the two currents moves southward with its lower extremity, or region of lowest barometer, in front, while the plane itself is more or less inclined northward. Hence the barometer shows no change until this region of lowest barometer moves over it, when it suddenly falls g but it is then already in the most dangerous part of the storm, and its warning, therefore, comes too late; while the clouds, if properly observed, always give warning in time to provide against the dangers of such a storm. ”

“ Sometimes these clouds, before reaching the zenith, will recede and disappear beneath the southern horizon. This indicates a backward oscillation of the southern current, caused by the greater resistance of the polar current. But in such case the stratus clouds will reappear next day, or sooner, and uniting and, becoming denser, they will advance over the zenith, and cover the whole heavens, discharging rain, snow, or sleet, according to the thermal conditions present. ”

“ Buys-Ballot, of Utrecht, that "the wind always blows from the place of highest to that of lowest barometer, turning by the rotation of the earth to the right on the northern hemisphere, and to the left on the southern hemisphere." ”

“ A storm must be treated as an individual which is subject to development. This is difficult, on account of the nature of the subject, but it is possible and essential. We must take the storm at its earliest appearance, and not lose sight of it for one moment until we know it throughout its whole extent, in all its parts, from beginning to end. ”

“ In endeavoring to interpret the weather, we are in the position of a man who hears at intervals a few fragments of a long history related in a prosy, unmethodical manner. A host of circumstances omitted or forgotten, and the want of connection between the parts, prevent the hearer from obtaining possession of the entire story. ”

“ They are the most violent and destructive of all storms, as well as the most complicated and difficult to understand and explain. They are the offspring of progressive polar or summer storms, and in the temperate zone occur only during summer. ”