An element that can control current without moving parts, heated filaments, or vacuum gaps.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

(1) The ratio of the speeds of a chemical reaction at two temperatures differing by 10

A temperature scale on which the freezing point of water equals 32

An elongated area of relatively low atmospheric pressure. Usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow. The opposite of a ridge.

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

A thermometer. the sensitive element of which consists of two metal strips which have different coefficients of expansion and are brazed together. The distortions of the system in response to temperature variations are used as a measure of temperature. It ...

Any twelve-month period, usually selected to begin and end during a relative dry season. Used a basis for processing streamflow and other hydrologic data. The period from October 1 to September 30 is widely used in the U.S.

The addition of one or more redundant bits to information to verify its accuracy.

A hydrostatic principle that pressure supplied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the containing vessel.

The direction toward which the wind is blowing; with the wind.

Facing away from the wind.

Having a specific relationship to a time base or clock. In synchronous communications, data characters are sent according to a timing signal which synchronizes the two communicating devices.

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.

A unit of luminance (or brightness) equal to 1/6 candles per square centimeter.

A current meter consisting of six conical cups, mounted around a vertical axis, which rotate and generate a signal with each rotation. Tail vanes and a heavy weight stabilize the instrument.

The decrease of an atmospheric variable with height, the variable being temperature, unless otherwise specified.

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.