Science for beginners . Fig. 124.—Photograph of two cloud sheets. Taken from an airplaneflying between the two cloud sheets. The cloud sheet below the air-plane is stratus clouds; the cloud sheet above the airplane is alto-stratus. The stratus sheet below receives the lights and the shadowsof the upper sheet just as the surface of a body of water would. (Air-plane photo, Monthly Weather Reveiw.) 184. The Forming of Ground Fog.—While dew or frost isforming, the air often remains clear. But the cooling maygo far enough to chill the whole mass of air near the ground tobelow its dew point. Then pa
Science for beginners . Fig. 124.—Photograph of two cloud sheets. Taken from an airplaneflying between the two cloud sheets. The cloud sheet below the air-plane is stratus clouds; the cloud sheet above the airplane is alto-stratus. The stratus sheet below receives the lights and the shadowsof the upper sheet just as the surface of a body of water would. (Air-plane photo, Monthly Weather Reveiw.) 184. The Forming of Ground Fog.—While dew or frost isforming, the air often remains clear. But the cooling maygo far enough to chill the whole mass of air near the ground tobelow its dew point. Then part of the vapor within thechilled air is condensed into very small particles of water thatremain suspended in the air as Fog. Sometimes this fog maybe seen first in the few inches of air next the ground, graduallydeepening as the air chills higher. Deep, widespread fogs are often formed by the mixing of THE WATER VAPOR OF THE AIR 169. FlG. 125.—Upper third cirrus clouds; lower half cirro-stratus. Cir-rus are light feathery clouds, more or less scattered. When they havethe form of plumes with frayed or torn edges, and are moving rapidly,they usually indicate increasing cloudiness and rain or snow. Cirrusmoving very slowly seldom indicate an approaching storm. In temper-ate zones cirrus and cirro-stratus nearly always move from a westerlydirection. The thickening of cirrus into cirro-stratus, as shown here,often indicates rain or snow. The clouds seem to thicken graduallyuntil the sky is hidden. This thickening is sometimes partly due tothe growth of the clouds themselves; usually it is caused mainly by thecoming of denser masses as the earlier clouds pass on. ; • ? . -. ? ? ? .... ,,:.. .. Fig. 126.—Fair-weather cumulus clouds. This type of cumulus isoften seen. Note the level bases and rounded tops. (The bases are allat the same height, though the distant bases appear lower becausefarther away.) The
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscience, bookyear1921
