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

A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.

Same as fogbow.

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

The distance or length of flow of the air past a point during a given interval of time.

The correctable part of the inaccuracy of an instrument.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

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.

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

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

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 ...

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays, between 0.02 and 0.4 micron (200 and 4000 angstrom).

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

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.

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

A common unit used in measurement of atmospheric pressure. Defined as that pressure exerted by a one-inch column of mercury at standard gravity and a temperature of 0'C.

A type of pressure-plate anemometer in which the plate, restrained by a stiff spring, is held perpendicular to the wind. The wind-activated motion of the plate is measured electrically. The natural frequency of this system can be made high enough so that ...

See radar theodolite, radio direction-finder.

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

Precipitation caused by the ascent of moist air over an orographic barrier such as a Mountain range.