Old snow that has become granular and compacted as a result of melting and refreezing.

A continuous-recording barometer.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

A polarimeter utilizing a Wollaston prism as a polarizer and a Nicol prism as an analyzer.

A special form of the aspiration psychrometer. developed by Assmann, in which the thermometric elements are well shielded from radiation. Psychrometric measurements may be taken with the instrument in the presence of direct solar radiation.

A local variation of the wind vector or any of its components in a given direction.

An instrument developed by K. Angstrom for measuring the effective terrestrial radiation. It consists of four manganin strips, of which two are blackened and two are polished. The blackened strips are allowed to radiate to the atmosphere while the polishe ...

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

Same as dropsonde.

Of or pertaining to rain.

Temperarure at which a liquid solidifies under any given set of conditions. It may or may not be the same as the melting point or the more rigidly defined true freezing point or (for water) ice point.

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

Instrument for measuring the depth of water from precipitation that is assumed to be distributed over a horizontal, impervious surface and not subject to evaporation.

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.

An instrument for measuring the intensity of light or the relative intensity of a pair of lights. Also called an illuminometer. If the instrument is designed to measure the intensity of light as a function of wavelength, it is called a spectrophotometer. ...

A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

A hypothetical, ideal body which absorbs completely all incident radiation. independent of wavelength and direction. No actual substance behaves as a true black body, although platinum black and other soots rather closely approximate this ideal. However, ...

The energy of any type of electromagnetic radiation. Also called radiation.

A generic term for any machine that enables a human being to communicate with a computer.

A recording anemoclinometer.