An automatic, recording cloud height indicator.

A thin metal disc partially evacuated of air used to measure atmospheric pressure by measuring its expansion and contraction.

An instrument for measuring the difference of the solar radiation falling on both sides of a horizontal surface from the whole hemisphere.

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

The level at which ice crystals and snowflakes melt as they descend through the atmosphere.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

Automated Local Evaluation in Real Time. Network of automatic rain gauges that transmit via VHF radio link when precipitation occurs. Some sites are also equipped with other sensors such as temperature, wind, pressure, river stage or tide level. More info ...

See radiosonde commutator.

Radiation with wavelengths greater than 4 microns. (In meteorology, same as infrared radiation.)

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

An instrument which measures the intensity of radiation by determining the amount of chemical change( or fluorescence produced by that radiation.

The process of modifying some characteristic of a wave (the carrier) so that it varies in step with the instantaneous value of another wave (the modulating wave) in order to transmit a message. The modified characteristic may be frequency, phase, and/or a ...

A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

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

A hypothetical body which absorbs some constant fraction, between zero and one, of all electromagnetic radiation incident upon it, which fraction is the absorptivity and is independent of wavelength. Compare to black body, white body.

An instrument for determining the degree of polarization of light. See photopolarimeter.

A recording weight barometer.

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

Emission or transfer of energy in the form of electromagnetic waves or particles.

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.