The Principles of Aërography

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Rand McNally, 1917 - 318 Seiten
 

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Seite 168 - To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. To the end of the twine, next the hand, is to be tied a silk ribbon, and where the silk and twine join, a key may be fastened.
Seite 167 - Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended...
Seite 168 - This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet ; and care must ba taken that the twine does not touch the frame of the door or window.
Seite 172 - The turmoil compels mechanical contact between the drops, whereupon the charges break down the surface tension and insure coalescence. Hence, once started, the electricity of a thunderstorm rapidly grows to a considerable maximum. " After a time the larger drops reach, here and there, places below which the updraft is small — the air cannot be rushing up everywhere — and then fall as positively charged rain, because of the processes just explained. The negative electrons in the meantime are carried...
Seite 203 - ... if it is isolated; (c) if it is upon high ground; (d) if it is well (deeply) rooted; (e) if it is the best conductor at the moment of the flash ; that is, if temporary conditions, such as being wet by rain, transform it for the time from a poor conductor to a good one. 5. Lightning may bring about a forest fire by igniting the tree itself, or the rjumus at its base.
Seite 115 - ... of the. sailors. 8. Cumulus (Cu.) . Wool-pack clouds. Thick clouds whose summits are domes with protuberances, but whose bases are flat. These clouds appear to form in a diurnal ascensional movement, which is almost always apparent. When the cloud is opposite the sun, the surfaces which are usually seen by the observer are more brilliant than the edges of the protuberances. When the illumination comes from the side, this cloud shows a strong actual shadow; on the sunny side of the sky, however,...
Seite 186 - ... strong convection current is essential to the formation of hail, that it can occur only where this convection exists; that is, in the front portion of a heavy to violent thunderstorm. Some meteorologists hold that the roll scud between the ascending warm and descending cold air is the seat of hail formation, but this is a mistaken assumption. Centrifugal force would throw a solid object, like a hailstone, out of this roll probably before a single turn had been completed. Besides, and this objection...
Seite 290 - Calm Light air Light breeze Gentle breeze Moderate breeze Fresh breeze Strong breeze Moderate gale Fresh gale Strong gale Whole gale Storm Estimatin Observations at sea Sea like mirror.
Seite 115 - Cu.). Large balls or rolls of dark cloud, which frequently cover the whole sky, especially in winter, and give it at times an undulated appearance. The stratum of strato-cumulus is usually not very thick, and blue sky often appears in the breaks through it. Between this form and the alto-cumulus all possible gradations are found. It is distinguished from nimbus by the ball-like or rolled form, and because it does not tend to bring rain.
Seite 117 - From their base generally fall local showers of rain or snow, and sometimes hail or sleet. The upper edges are either of compact cumulus-like outline, and form massive summits, surrounded by delicate false cirrus, or the edges themselves are drawn out into cirrus-like filaments. This last form...

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