Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval. Also called fluctuation velocity.

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 ...

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

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, ...

A power supply which achieves its output regulation by means of one or more active power handling devices which are alternately placed in the "off" or "on" states. It is more efficient than linear supplies which vary the conduction of power devices to ach ...

Any meteorological instrument, such as a radiosonde, in which the recording apparatus is located at some distance from the measuring apparatus.

See instrument error, observational error. random error, standard error, systematic error.

Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.

A thermometer designed for use in measuring the temperature of sea water. One form consists of a mercury-in-glass thermometer protected by a perforated metal case. Another form consists of a mercury-in-glass thermometer surrounded by a metal case which fo ...

Same as balloon cover.

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 line drawn through points of equal humidity on given surface.

A photometer that measures the received intensity of a distance tight source.

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

The amount of precipitation falling in one day, or other specified period, that is likely to be equalled or exceeded in any given place only once in a century. That is, a precipitation amount that has a return period of 100 years.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

A photoelectric spectrophotometer which is used in the determination of the ozone content of the atmosphere.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

A plastic molding component formed by the reaction of phenol and formaldehyde. It can be heavily reinforced or "filled" with glass fibers or other materials. Phenolics are known for their high impact strength, excellent wear characteristics, and dimension ...

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 ...