Of or pertaining to the air, atmosphere, or aviation. Also, same as antenna.

Old snow that has become granular and compacted as a result of melting and refreezing.

Precipitation composed of white or translucent ice crystals, chiefly in complex branched hexagonal forms.

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

A polarimeter utilizing a Wollaston prism as a polarizer and a Nicol prism as an analyzer.

The process by which small particles suspended in a medium of a different refractive index diffuse a portion of the incident radiation in all directions. In scattering no energy transformation results, only a change in the spatial distribution of the radi ...

Capacity of a soil or other surface to be penetrated by water sinking into the ground under the force of gravity. It thus expresses the rate of percolation.

A type of disk hardness-gauge, especially useful in relatively soft snow. See disk hardness gauge.

A fixed support for mounting maximum and minimum thermometers of the liquid-in-glass type. The support holds the thermometers at the correct operating attitude and also permits their rotation for resetting when desired.

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

A type of cooling-power anemometer based upon the principle that the time constant of a thermometer is a function of its ventilation.

An instrument for measuring the frost point of the atmosphere.

Abbreviation for radio frequency.

An instrument used to indicate wind direction.

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.

Area of a computer or other device where various logic and control elements are interconnected. Often a printed circuit board into which other circuit boards plug at right angles.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.