A very sensitive electrostatic electrometer for measuring small potential differences.

Same as an upper air observation, but commonly used to refer to a single complete radiosonde observation.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

A pressure tube anemometer, consisting of a pitot tube mounted on the windward end of a wind vane and a suitable manometer to measure the developed pressure and calibrated in units of wind.

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 pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

A type of wind vane having a split or V-shaped tail. The apex orients itself to the direction of the wind.

A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

Same as marine rainbow.

In thermodynamics, the integrating factor of the differential equation referred to as the first law of thermodynamics, In statistical mechanics, a measure of translational molecular kinetic energy (with three degrees of freedom). In general, the degree of ...

A unit of distance equal to 5280 feet. It is sometimes referred to as a land mile.

A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

Name applied to a class of instruments which measure the liquid content of the atmosphere.

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.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

A line drawn through geographical points where a given seasonal biological event occurs on the same date.

Sustained winds greater than or equal to 40 mph or gust greater than or equal to 58 mph.

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