Upwarddirected solar radiation, reflected by the earth's surface and the atmosphere.

General name for an instrument designed to measure the vertical component of the wind speed. See anemoclinometer.

Difference between the instantaneous wind velocity at a point and the mean wind velocity taken over a given time interval. Also called fluctuation velocity.

A thermograph in which ventilation is provided by a suction fan.

Wind with a speed between 17 and 21 knots (19 and 24 mph); Beaufort scale number 5.

An atmospheric phenomenon, other than clouds, which obscures a portion of the sky from the point of observation. Also called obscuration.

Solar radiation of selected wavelengths.

A nephoscope in which the motion of the cloud is observed by its reflection in a mirror.

A type of anemometer in which the rotation of an element serves to measure the wind. Rotation anemometers are divided into two classes; those in which the axis of rotation is horizontal, such as the windmill anemometer, and those in which the axis of rota ...

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.

An instrument designed to record the duration of sunshine at a given location without regard to intensity. See Campbell- Stokes recorder, Jordan sunshine recorder, Marvin sunshine recorder, Pers sunshine recorder.

A continuous-recording barometer.

Pertaining to measurements or devices in which the output vanes in discrete steps, i.e. on-off or pulse signals. Compare to analog.

Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed.

The frequency of a carrier wave.

Board that holds graph paper on which is plotted information obtained from a pilot-balloon observation.

Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e. cubic feet per second.

Eluding precise prediction, completely irregular.

An instrument which records the duration of sunshine and gives a quantitative measure of the amount of sunshine by the action of the sun's rays upon blueprint paper. A type of sunshine recorder.

A modification of the dew cell used in radiosonde equipment.