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chlorofluorocarbons

(Encyclopedia)chlorofluorocarbons klōrˌəflo͝orˈəkärˌbənz, klôrˌ– [key] (CFCs), organic compounds that contain carbon, chlorine, and fluorine atoms. CFCs are highly effective refrigerants that were deve...

cloud

(Encyclopedia)CE5 Approximate heights of some types of clouds cloud, aggregation of minute particles of water or ice suspended in the air. Cloudiness (or proportion of the sky covered by any form of cloud),...

rocket, in aeronautics

(Encyclopedia)CE5 Relative positions of the components of the Saturn V rocket, the U.S. space vehicle used in the moon missions rocket, any vehicle propelled by ejection of the gases produced by combustion of s...

Alpha Centauri

(Encyclopedia)Alpha Centauri ălˈfə sĕntôrˈē [key], brightest star in the constellation Centaurus and 3d-brightest star in the sky; also known as Rigil Kent or Rigil Kentaurus; 1992 position R.A. 14h39.1m, De...

Conrad, Joseph

(Encyclopedia)Conrad, Joseph, 1857–1924, English novelist, b. Berdichev, Russia (now Berdychiv, Ukraine), originally named Jósef Teodor Konrad Walecz Korzeniowski. Born of Polish parents, he is considered one of...

hardening

(Encyclopedia)hardening, in metallurgy, treatment of metals to increase their resistance to penetration. A metal is harder when it has small grains, which result when the metal is cooled rapidly. Sometimes small ar...

Montreal Protocol

(Encyclopedia)Montreal Protocol, officially the Protocol on Substances That Deplete the Ozone Layer, treaty signed on Sept. 16, 1987, at Montreal by 25 nations; 197 nations are now parties to the accord. The protoc...

methane

(Encyclopedia)methane mĕthˈān [key], CH4, colorless, odorless, gaseous saturated hydrocarbon; the simplest alkane. It is less dense than air, melts at −184℃, and boils at −161.4℃. It is combustible and c...

lightning

(Encyclopedia)lightning, electrical discharge accompanied by thunder, commonly occurring during a thunderstorm. The discharge may take place between one part of a cloud and another part (intracloud), between one cl...

xenon

(Encyclopedia)xenon zēˈnŏn [key] [Gr.,=strange], gaseous chemical element; symbol Xe; at. no. 54; at. wt. 131.293; m.p. −111.9℃; b.p. −107.1℃; density 5.86 grams per liter at STP; valence usually 0. Xeno...