National Weather Service. Administered by the U.S. Department of Commerce.

A graphical representation of stage or discharge at a point on a stream as a function of time.

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.

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 thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

Reduction of visibility by strong winds blowing across dry ground with little or no vegetation. Visibilities of 1/8 mile or less over a widespread area are criteria for a Blowing Dust Advisory.

A measure, proposed by Angstrom, of the precipitation effectiveness of a region.

Sir Napier Shaw's name for the approximate absolute temperature scale,

The transducer of any hygrometer, i.e. that part of a hygrometer that quantitatively "senses" atmospheric water vapor.

Name sometimes given to a transmissometer.

Thermometer used for measuring the highest temperature attained during a given interval of time, for example, a day.

Hygrometer in which the dew (frost) point is determined by observing the temperature of an artificially cooled surface at the moment at which dew (frost) first appears on it.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifteenth contact of the commutator, up to a number determined by the design of the commutator, and each fifth contact thereafter. This signal is t ...

A counterclockwise change in wind direction. Backing winds with height are indicative of cold air advection (CAA).

A unit of energy equal to 1.356joules.

The temperature registered by a thermometer with its bulb at the level of the tops of the grass blades in short turf.

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

Instrument used to measure the amount of water evaporated from the soil surface during a given time interval.

In meteorology, an area of low pressure; a low or trough.

A component of the wind (often using Cartesian coordinates. i.e. X and Y wind vectors). Also, an arrow representing wind velocity, drawn to point in the direction of the wind and with a length proportional to wind speed.