The visibility along an identified runway, determined from a specified point on the runway with the observer facing in the same direction as a pilot using the runway. Compare to runway visible range.

An apparatus, used in studying soil temperatures, for measuring the total supply of heat during a given period.

A wooden enclosure about sixteen feet square and eight feet high with a precipitation gauge at its center. The function of the fence is to minimize eddies around the gauge and thus insure a catch that is representative of the actual rainfall or snowfall.

A coating of ice, generally clear and smooth. formed by the freezing of supercooled water on a surface.

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

The array of indicating marks and figure in relation to which the position of an index is observed, i.e. a scale plate on a recorder.

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

A temperature-sensing element which converts thermal energy directly into electrical energy. In its basic form it consists of two dissimilar metallic conductors connected in a closed loop. Each junction forms a thermocouple. If one thermocouple is maintai ...

An instrument used to measure and record earthquake vibrations and other earth tremors.

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.

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

A type of photoelectric photometer used to measure high-altitude winds on the assumption that stellar scintillation is caused by atmospheric inhomogeneities being carried along by wind near the tropopause level.

Rate of wind movement in distance per unit time.

A mercury barometer which measures atmospheric pressure by weighing the mercury in the column or cistern.

That portion of the atmosphere which is above the lower troposphere. Generally applied to levels above 850 mb.

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

A recording weight barometer.

The attenuation of light.

A device used to switch electrical current at a selectable setpoint temperature.

Any twelve-month period, usually selected to begin and end during a relative dry season. Used a basis for processing streamflow and other hydrologic data. The period from October 1 to September 30 is widely used in the U.S.