Wind with a speed between 7 and 10 knots (8 and 12 mph), Beaufort scale number 3.

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 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.

A colorless and odorless gaseous element. The lightest and apparently the most abundant chemical element in the universe. However, it is found only in trace quantities in the observable portion of our atmosphere, only about 0.00005 percent by volume of dr ...

A system in which radar techniques are used to determine the range, elevation, and azimuth of a radar target carried a!oft by a radiosonde, so that wind data may be obtained along with the other meteorological data.

A polariscope consisting of a specially constructed double plate polarizer and a tourmaline plate analyzer. Polarized light passing through the instrument is indicated by the presence of parallel colored fringes, while unpolarized light results in a unifo ...

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

In Jeffreys' classification, a wind for which the pressure force exactly balances the viscous force, in which the vertical transfers of momentum predominate.

An accumulation of granular ice tufts on the windward sides of exposed objects that is formed from supercooled fog or cloud and built out directly against the wind.

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

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

Wind with a speed between 22 and 27 knots (25 and 31 mph); Beaufort scale number 6.

The condition of the atmosphere when the amount of water vapor present is the maximum possible at the existing temperature.

Negative Vorticity Advection.

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

A hygrometer using goldbeater's skin as the sensitive element. Variations of the physical dimensions of the skin caused by its hygroscopic character indicate relative humidity. (Note: Goldbeater's skin is the prepared outside membrane of the large intesti ...

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

An anemometer utilizing the principle that the pitch of the aeolian tones generated by air moving past an obstacle is a function of the speed of the air. Largely a curiosity and has been put to no practical application in modem meteorology.

Same as instrument shelter.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.