A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

An instrument for determining the direction of cloud motion. There are two basic designs of nephoscope, the directvision nephoscope and the mirror nephoscope.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

The statement that the viscosity of air is independent of the density of air.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

See radar theodolite, radio direction-finder.

NEXt Generation RADar. A NWS network of about 140 Doppler radars operating nationwide.

A temperature telemeter.

The correctable part of the inaccuracy of an instrument.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

A thermometer with a muslin-covered bulb which is moistened. used to measure wet-bulb temperature.

Same as instrument shelter.

Same as fogbow.

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.

Generic term for rapid variations in apparent position, brightness, or color of a distant luminous. object viewed through the atmosphere.

A conductor or system of conductors for radiating and/or receiving radio energy. Also called aerial.

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves.

A device, similar to a potometer, for measuring transpiration, consisting of a vessel containing soil in which one or more plants are rooted and sealed so that water can escape only by transpiration from the plant.

A point (or line) on a scale used for reference or comparison purposes. In calibration of meteorological thermometers, for example, the fiducial points are 100