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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...

Solidarity

(Encyclopedia)Solidarity, Polish independent trade union federation formed in Sept., 1980. Led by Lech Wałęsa, it grew rapidly in size and political power and soon posed a threat to Poland's Communist government ...

redstart

(Encyclopedia)redstart, common name for an Old World thrush of the genus Phoenicurus, family Turdidae. A small, slender-legged songbird, it is found in woodlands, parks, and heaths. The European redstart, P. phoeni...

Thíra

(Encyclopedia)Thíra or Thera both: thērˈə [key], volcanic island (1991 pop. 9,360), c.30 sq mi (80 sq km), SE Greece, in the Aegean Sea. One of the Cyclades, Thíra is also known as Santorini, for St. Irene, th...

Yellowstone National Park

(Encyclopedia)Yellowstone National Park, 2,219,791 acres (899,015 hectares), the world's first national park (est. 1872), NW Wyo., extending into Montana and Idaho. It lies mainly on a broad plateau in the Rocky Mt...

maple

(Encyclopedia)maple, common name for the genus Acer of the Aceraceae, a family of deciduous trees and shrubs of the Northern Hemisphere, found mainly in temperate regions and on tropical mountain slopes. Acer, the ...

Hawaii, island, United States

(Encyclopedia)Hawaii, island (2020 pop. 200, 629), 4,037 sq mi (10,456 sq km), largest and southernmost island of the state of Hawaii and coextensive with Hawaii co.;...

rue

(Encyclopedia)rue, common name for various members of the family Rutaceae, a large group of plants distributed throughout temperate and tropical regions and most abundant in S Africa and Australia. Most species are...

Pliocene epoch

(Encyclopedia)Pliocene epoch plīˈəsēn [key], fifth epoch of the Cenozoic era of geologic time (see Geologic Timescale, tablegeologic timescale, table), from 5.1 to 2 million years ago. By the beginning of the P...

sodium

(Encyclopedia)sodium, a metallic chemical element; symbol Na [Lat. natrium]; at. no. 11; at. wt. 22.98977; m.p. 97.81℃; b.p. 892.9℃; sp. gr. 0.971 at 20℃; valence +1. Sodium is a soft, silver-white metal. Ext...