A unit that represents one degree of deviation from a reference point in the mean daily outdoor temperature (usually 65

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

An increase or amplification. There are two general usages of the term in radar meteorology: (a) antenna gain (or gain factor) is the ratio of the power transmitted along the beam axis to that of an isotropic radiator transmitting the same total power; an ...

Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.

A pressure tube anemometer, consisting of a pitot tube mounted on the windward end of a wind vane and a suitable manometer to measure the developed pressure and calibrated in units of wind.

A measure of the intensity of gusts given by the ratio of the total range of wind speed between gusts and the intermediate periods of lighter wind to the mean wind speed, averaged over both gusts and lulls.

A thermometer based upon the principle that the velocity of a sound wave is a function of the temperature of the medium through which it passes. Sonic thermometers possess very short time-constants and eliminate radiation error.

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

A recording weight barometer.

Abbreviation for radio frequency.

A method of winds aloft observation essentially the same as a pilot balloon observation except the height data is derived from the radiosonde observation rather than from assumed ascension rates.

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

The distance or length of flow of the air past a point during a given interval of time.

Frozen or partly frozen rain.

To free something from the binding action of ice by warming it to a temperature above the melting point of ice. Also, a warm spell when ice and snow melt.

A recording hair hygrometer.

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

The cardinal points of the compass, i.e. north, south, east, west.

A type of pressure-tube anemometer, named after the inventor.