The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

An increase in the central pressure of a pressure system; opposite of a deepening. More commonly applied to a low rather than a high.

A form of data transmission in which the bits of each character are sent one at a time along a single communication path. Compare to parallel data transmission.

A method of upper air observation consisting of an evaluation of the wind speed and direction, temperature, pressure, and humidity aloft by means of a balloon-borne radiosonde tracked by radar or a radio theodolite.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

A measure of the attenuation due to scattering, of light as it traverses a medium containing scattering particles.

The total area drained by a river and its tributaries. Same as river basin.

A type of pressure-plate anemometer in which the plate, restrained by a stiff spring, is held perpendicular to the wind. The wind-activated motion of the plate is measured electrically. The natural frequency of this system can be made high enough so that ...

A wind blowing in a direction perpendicular to the course of a moving object.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

A method of winds aloft observation accomplished by tracking a balloon-borne radar target or radiosonde with either radar or a radio theodolite.

A graphical device used for the determination of the speed of the geostrophic wind from the isobar or contour-line spacing on a synoptic chart.

See evaporative opportunity.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

The difference between temperature measurements taken at two significant levels above the ground. Temperatures at 10 and 40 meters are commonly used.

Same as instrument shelter.

The part of a measuring instrument which responds directly to changes in the environment.

A scale with the ice point at zero degrees and the boiling point of water at 80 degrees, with pressure of one atmosphere.

In thermodynamics, the integrating factor of the differential equation referred to as the first law of thermodynamics, In statistical mechanics, a measure of translational molecular kinetic energy (with three degrees of freedom). In general, the degree of ...