A unit of signaling speed representing the number of code elements sent per second; often, bits per second.

A thermometer designed for use in measuring the temperature of sea water. One form consists of a mercury-in-glass thermometer protected by a perforated metal case. Another form consists of a mercury-in-glass thermometer surrounded by a metal case which fo ...

A rain gauge which automatically records the amount of precipitation collected, as a function of time.

An instrument, located at the surface observing station, which is used to record the data presented by a radiosonde aloft.

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

Same as pitot tube.

A high-altitude sounding system consisting of a small solid- propellant research rocket carried aloft by a large plastic balloon. The rocket is fired near the maximum altitude of the balloon flight.

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.

An instrument for measuring the pressure of the atmosphere. The two principle types are aneroid and mercurial.

A thermometer used in aircraft which automatically corrects for adiabatic and frictional temperature rises by imparting a rotary motion to the air passing the thermal sensing element.

The height of the cloud base above the local terrain.

Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.

The mass density of a parcel of air expressed in units of mass per volume.

A unit of energy equal to 1.356joules.

An instrument used to measure the water vapor content of the air. A type of hygrometer. It consists of a wet-bulb and a dry-bulb thermometer. See aspiration psychrometer, Assmann psychrometer. hygrodeik, sling psychrometer.

An anemometer which measures wind speed by means of the properties of wind-borne sound waves. It operates on the principle that the propagation velocity of a sound wave in a moving medium is equal to the velocity of sound with respect to the medium plus t ...

The succession of stages through which water passes on the ground and in the atmosphere: evaporation from land or bodies of water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.

See gain.

Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system. Compare to adiabatic process.

The indicating part of an instrument. For example, the hand of a watch or the meniscus of a mercury column.