An instrument which automatically determines the size distribution of raindrops.

Wind with a speed between 34 and 40 knots (39 and 46 mph); Beaufort scale number 8.

The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

A balloon designed to float at a constant pressure level. This may be accomplished by a pressure valve which controls the release of ballast so as to maintain flight above a selected pressure level until the supply of ballast is exhausted. See Moby Dick b ...

Apparatus consisting of (a) standard radiosonde and radiosonde ground equipment to obtain upper-air data on pressure, temperature, and humidity, and (b) a self-tracking radio direction-finder to provide the elevation and azimuth angles of the radiosonde s ...

A wind (or component thereof) directed down the slope of an incline and caused by greater air density near the slope than at the same levels some distance horizontally from the slope. Also called drainage wind and sometimes called katabatic wind.

An instrument for taking photographs of an image of the sun in monochromatic light.

Frozen or partly frozen rain.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

A special form of the aspiration psychrometer. developed by Assmann, in which the thermometric elements are well shielded from radiation. Psychrometric measurements may be taken with the instrument in the presence of direct solar radiation.

A synoptic code approved by the World Meteorological Organization in which the observable meteorological elements are encoded and transmitted in "words" of five numerical digits length. Often abbreviated synoptic code.

A c.g.s. (centimeter-gram-second) unit of mass. Originally defined as the mass of 1 cubic centimeter of water at 4

The water portion of the earth as distinguished from the solid part, called the lithosphere, and from the gaseous outer envelope, called the atmosphere.

An instrument used to measure the amount of dew formed on a given surface.

An instrument for determining the direction from which radio waves approach a receiver. It may consist of a manually operated direction indicator, or it may use a servo system to position the antenna automatically in the direction of the incident waves. T ...

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

The element directly responsive to the value of the measured variable.

A hygrometer which determines the amount of precipitable moisture in a given region of the atmosphere by measuring attenuation of radiant energy caused by the absorption bands of water vapor.