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humidity

(Encyclopedia)humidity, moisture content of the atmosphere, a primary element of climate. Humidity measurements include absolute humidity, the mass of water vapor per unit volume of natural air; relative humidity (...

liter

(Encyclopedia)liter, abbr. l, unit of volume in the metric system, defined since 1964 as equal to 0.001 cubic meters, or 1 cubic decimeter. A cube that has each of its edges equal to 10 centimeters has a volume of ...

infrared radiation

(Encyclopedia)infrared radiation, electromagnetic radiation having a wavelength in the range from c.75 × 10−6 cm to c.100,000 × 10−6 cm (0.000075–0.1 cm). Infrared rays thus occupy that part of the electrom...

farad

(Encyclopedia)farad fărˈəd [key] [for Michael Faraday], unit of electrical capacitance, equivalent to 1 coulomb of stored charge per volt of applied potential difference. ...

opus

(Encyclopedia)opus ōˈpəs [key] [Lat.,=work], in music, term used in cataloging a composer's works, designating either a single composition or a group published together or considered a unit. Opus numbers assigne...

period, in geologic time

(Encyclopedia)period, unit of time on the geologic timescale. Periods are shorter than an era and longer than an epoch. Periods are of variable length, generally lasting tens of millions of years, with characterist...

nitrous oxide

(Encyclopedia)nitrous oxide or nitrogen (I) oxide, chemical compound, N2O, a colorless gas with a sweetish taste and odor. Its density is 1.977 grams per liter at STP. It is soluble in water, alcohol, ether, and ot...

Shklovsky, Iosif Samuilovich

(Encyclopedia)Shklovsky, Iosif Samuilovich yôsˈĭf səmo͞oēlˈəvĭch shklŏfˈskē [key], 1916–85, Soviet astronomer. He was head of the department of radio-astronomy at the Sternberg Astronomical Institute,...

hertz

(Encyclopedia)hertz hûrts [key] [for Heinrich R. Hertz], abbr. Hz, unit of frequency, equal to 1 cycle per second. The term is combined with metric prefixes to denote multiple units such as the kilohertz (1,000 Hz...

Holston

(Encyclopedia)Holston, river, c.120 mi (190 km) long, formed by the uniting of its northern and southern forks, NE Tenn., and flowing SW through the Great Appalachian Valley, joining the French Broad River at Knoxv...