Page:Dictionary of aviation.djvu/139

 DICTIONARY OF AVIATION 115

gondola 'gonda-te w. a boat-like car of a dirigible balloon.

gore go:z n. one of the many triangular or lune-shaped pieces of silk or other material which together ferm the envelop of the gasbag of a balloon.

gossamer 'gosa-maz n. a web-like or gauzy fabric or stjuc- ture : as, the *gessamer wings of an insect.

gossamer-like 'gosamaz^aik adj. like gossamer; web-like, gauzy : as, *gossamer-like construction.

gourd-whistle 'gu:zd,wis3l n. a light wind-blown whistle made of tubes fastend to a gourd body or wind-chest, at- tacht by the Chinese to the tails of flying pigeons.

governing-plane 'gAV9<min,pjLeen n. one of the aeroplanes forming part of a dirigible balloon or airship and used to govern or control the direction or equilibrium of the craft.

gradient 'gzee-di-snt n. a series or system of steps, grades, or degrees; specifically, the rate at which a variable quantity changes; rate of variation; rate of change.

adiabatic gradient, the vertical gradient of the tempera- ture of any portion of the atmosfere under adiabatic con- ditions; the rate of change in the temperature of the air (with change of altitude) caused by change of volume and concomitant transformation of internal energy of the air concernd, but not the result of any transference of heat to or from the surrounding air; the rate at which the tempe- rature of the atmosfere varies (as mesured at different heights above the earth) when the variation of its tempera- ture is due solely to expansion or compression of the air resulting from a decrease or an increase in the external air-pressure and the accompanying absorption or evolution of internal heat.

barometric gradient, the gradient of barometric pressure with distance; the rate of change of atmosfenc pressure along the surface of the earth, usually mesured (en the wether-map) along a line perpendicular to the isobars at any point.

critical barometric gradient, the barometric gradient which would be maintaind under stedy wind-conditions; the rate at which atmosfenc pressure along the surface of the earth would vary under the influence of a stedy wind or stedy system of winds.

cyclonal gradient, the barometric gradient directed toward the center of a cyclone; the rate at which the atmosfenc pressure along the earth's surface would vary if mesured (on the wether-map) along a line extending from any given point toward the central point of minimum pressure in a rotary system of winds.

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