84 DICTIONARY OF AVIATION
duration-contest djo'ee-$9n,kon-test n. a contest as to duration of flight; a competitiv trial of flyers as to capac- ity to stay up in the air in continuous flight without alighting.
duration-prize djo'zee-Jan^saiz n. a prize or premium of- ferd or won for flight of long duration ; a tjofy for longest continuous v light without alighting.
dusk dAsk n. gloom, shade; the darker stage of twilight just before night; also, the stage of partial darkness just before dawn or daybreak.
dusky 'dAski adj. somewhat dusk or dark; darkish, gloomy, shadowy.
dust dAst n. earth or other selid matter in the form of fine dry particles, floating in the air; powdery or granular matter in the atmosf ere : as, a cloud of *dust.
dust-counter 'dAS^kaun-tae n. an instrument for mesurins the amount of dust or particles of selid matter in the air or atmosfere. compare coniscope.
dust-fog 'dAst,feg n. a tuhitish feg fermd of the finest mist or vapor^dust; dustevapor fog.
dust-haze 'dAst,heez n. a haze, or misty appearance of the atmosfere, usually of reddish or yellowish hue, consisting ef or due to dust.
dustiness 'dAsti-nis n. the state of being dusty or contain- ing dust; dusty condition of the air or atmosfere.
dust-shower 'dASt,$au-3z n. a shower or light downpour of dust (with or without rain or snow) due to a cloud of dust having been carried into the upper atmosfere and precipi- tated, compare seatdust.
dust-vapor 'dAst,vee-p9z n. same meaning as vaporzdust.
dust-wind 'dAst,wind n. a wind that brings dustestorms, such as the northwesterly gales on the eastern coast of Australia.
dust-wisp 'dAst,wisp n. a wisp or delicate spray or streak of dust or ice^particles, usually of grayish^iuhite color, floating high in the sky at sunset or sunrise.
dynamic di'naemic adj.
1. ef or relating to force or energy : contrasted with kine- matic f and often, loosely, with static.
dynamic cooling, the cooling or lowering of temperature of a portion of the atmosfere due to the expenditure of some of its internal heat energy in expansion occasiond by inferior atmosferic pressure from without.
dynamic heating, the heating, warming, or rise of tem- perature of a portion of the atmosfere due to compression occasiond by superior atmosferic pressure from without.