A box-like structure designed to protect certain meteorological instruments from exposure to direct sunlight, precipitation, and condensation, while at the same time providing adequate ventilation. Instrument shelters are painted white, have louvered side ...

Same as altimeter setting.

Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.

A unit of mass numerically equal to the molecular weight of the substance. The gram-mote or gram-molecule is the mass in grams numerically equal to the molecular weight, i.e. a gram-mole of oxygen is 32 grams.

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

Same as fogbow.

Programmable Read-Only Memory. Read-only memory which can be programmed by the user using a special hardware programmer.

Meteorological information issued by a watch office concerning the occurrence or forecast of weather phenomena which may affect the safety of aircraft operations.

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

The maximum deviation of any points from a straight line drawn as a "best fit" through the calibration points of an instrument with a linear response curve. Usually expressed as a percentage of full- scale range.

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.

(1) The initial component or the sensing element of a measuring system. For example, the receiver of a rain gauge is the funnel which captures the rain and the receiver of a thermoelectric thermometer is the measuring thermocouple. (2) An instrument used ...

In aviation terminology, route or terminal weather conditions of sufficiently low visibility to require the operation of aircraft under instrument flight rules.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

An instrument for measuring the relative speed of a fluid. It consists of a concentric pipe arrangement in which the inner pipe is open at one end and the outer pipe is perforated and closed at both ends. Each pipe is connected to a manometer. The unit is ...

Atmospheric layer throughout which there is no change of temperature with height, i.e. a zero lapse rate.

Root Mean Square. This notation is used frequently with error analysis. In that context, it is the square root of the arithmetic mean of the squares of the deviations of the individual calibration points from the theoretical or ideal response.

Video Display Terminal. An input and display device which includes a keyboard and a screen and allows a human to communicate with a computer.

Any and all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground.