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 DICTIONARY OF AVIATION 105

the cooling of the air below the dew^peint and consequent condensation of its water^vapor; an obscured condition of the atmosfere due to the presence of condenst water^vapor : as, an arctic *fog.

barometric fog, a feg due to a lowering of barometjic pressure and the consequent expansion and cooling of the air and condensation of water^vapor.

drifting fog, feg^like cloud luhich, tuhen in the form of a horizontal stratum, is cald stratus.

dry fog

1. a light fog (consisting of very fine particles of wa- ter) which does not wet objects with uuhich it comes in contact, compare wetting fog.

2. a haze due to the presence of dust, soot, or ashes, as from a prairie fire.

electric fog, a fog accompanied by electrical fenemena such as Saint Elmo's fire or balMightnmg.

radiation fog, a fog due to the cooling of the air conse- quent upon the radiation of its heat toward the colder earth below or sky above.

red fog, a fog or feg^like cloud of reddish hue, made up of dusteparticles, often seen off the northern part of the west coast of Africa.

wetting fog, a fog (composed of water^particles) which wets objects with which it comes in contact, compare dry fog.

wooly fog, a feg of wooblike appearance which moves slowly over the lower slopes of mountains in the nights time.

fog-alarm 'feg-9,la:zm n. an alarm, or signal by sound from a bell, gun, horn, or whistle, used in foggy wether, to indi- cate the presence of recks, lighthouses, or ships.

fog-bank 'feg,baenk n. a bank or wall^like mass or stratum of feg as seen from a distance; also, spcifically, a foggy or hazy appearance at sea, often taken for land, but vanishing as it is approacht; Cape Fly-away; No-man's Land; Dutch- man's Land.

fog-bell 'feg,bel n. a bell rung as a fog^signal.

fog-billow 'feg,bilo n. a billow or great surging wave of feg, observd by looking downward, as from a balloon, upon feg which is being acted upon by a gentle wind; a big feg? wave.

fog-bound 'feg,baund adj. bound, impeded, detaind, embar^ rast, or confined by feg, as a ship at sea.

fogbow 'feg,boo n. a bow or arch of light five degrees wide, slightly rosy on the outside, seen in a feg, and faintly re-

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