A liquid-in-glass or liquid-in-metal thermometer using mercury as the liquid.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

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

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

The inaccuracy that the manufacturer permits when the unit is calibrated in the factory.

An aviation weather forecast for a specific flight.

An ice coating with a consistency intermediate between glaze and rime.

Any soft, gentle breeze.

A navigational aid used to facilitate the landing of an aircraft at an airport in instrument weather, i.e. low visibility.

The ceiling classification which is applied when the ceiling height is determined by timing the ascent and disappearance of a ceiling balloon or pilot balloon.

See hydrologic accounting.

A line drawn through geographical points having the same pluvial index.

An instrument for the measurement of the rate of ice accretion on an unheated body.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

Precipitation of white, opaque, spherical or conical ice particles that are crisp and easily crushed and that have diameters of 2 to 5 mm.

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

An instrument designed to measure quantities of heat. Sometimes used in meteorology to measure solar radiation.

(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 ...

Facing away from the wind.

Apparatus consisting of (a) standard radiosonde and radiosonde ground equipment to obtain upper-air data on pressure, temperature, and humidity, and (b) a self-tracking radio direction-finder to provide the elevation and azimuth angles of the radiosonde s ...