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air navigation

(Encyclopedia)air navigation, science and technology of determining the position of an aircraft with respect to the surface of the earth and accurately maintaining a desired course (see navigation). Basic to air ...

ocean

(Encyclopedia)ocean, interconnected mass of saltwater covering 70.78% of the surface of the earth, often called the world ocean. It is subdivided into four (or five) major units that are separated from each other i...

chromosphere

(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...

fruit

(Encyclopedia)CE5 Types of fruit fruit, matured ovary of the pistil of a flower, containing the seed. After the egg nucleus, or ovum, has been fertilized (see fertilization) and the embryo plantlet begins to fo...

weather

(Encyclopedia)weather, state of the atmosphere at a given time and place with regard to temperature, air pressure (see barometer), wind, humidity, cloudiness, and precipitation. The term weather is restricted to co...

soil

(Encyclopedia)soil, surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus, the organic remains of decomposed vegetation. In agriculture, soil is the medium that...

diseases of plants

(Encyclopedia)diseases of plants. Most plant diseases are caused by fungi, bacteria, and viruses. Although the term disease is usually used only for the destruction of live plants, the action of dry rot and the rot...

Mesopotamia

(Encyclopedia)Mesopotamia mĕsˌəpətāˈmēə [key] [Gr.,=between rivers], ancient region of Asia, the territory about the Tigris and Euphrates rivers, included in modern Iraq. The region extends from the Persian...

skiing

(Encyclopedia)skiing, sport of sliding over snow on skis—long, narrow, flexible runners. Water skiing is a warm-weather sport in which a motor-propelled craft tows a skier through the water. Although its orig...

Pacific Ocean

(Encyclopedia)CE5 Pacific Ocean, largest and deepest ocean, c.70,000,000 sq mi (181,300,000 sq km), occupying about one third of the earth's surface; named by the explorer Ferdinand Magellan; the southern part i...