An instrument which measures the scattering function of particles suspended in a medium in order to determine the visual range through the medium. See visibility meter.

A self-recording thermometer.

A weakly colored lunar halo identical in form and optical origin to the solar parhelion.

in folklore, a name for fire.

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

Rate of wind movement in distance per unit time.

See gust and peak gust.

The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature. Usually expressed in percent.

A metallic element of atomic weight 200.6 1, unique (for metals) in that it remains liquid under all but very extreme temperatures.

The actual time during which physical events take place.

The difference between the outgoing infrared terrestrial radiation of the earth's surface and the downcoming infrared counterradiation from the atmosphere.

Either of two colored luminous spots that appear at points 22

The total infrared radiation emitted from the earth's surface. To be carefully distinguished from atmospheric radiation, effective terrestrial radiation, and insolation.

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.

An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

Any one of a family of circular arcs consisting of concentric colored bands, arranged from red on the inside to blue on the outside, which may be seen on a "sheet" of water drops (rain, fog, spray). The most common of the many possible is the primary rain ...

The measurement and computation of wind speeds and directions at various levels above the surface of the earth. Methods include pilot balloon observations, rabals, rawin or rawinsonde observations, radar tracking, or acoustic sounding.

The depth below which the ground is saturated with water. No water table exists if the ground water is confined by an overlying impermeable stratum, as in the case of artesian ground water.

Same as mercury barometer.

In general, the transformation of data from a "raw" form to some useable form. In meteorology, this often refers to the conversion of the observed value of an element to the value which it would theoretically have at some selected or standard level. The m ...