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

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.

A radiosonde whose carrier wave is switched on and off in such a manner that the interval of time between the transmission of signals if a function of the magnitude of the meteorological elements being measured.

A pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

A recording weight barometer.

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

Occupational Safety and Health Administration. A regulatory office of the U.S. Department of Labor.

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

A vector term which includes both wind speed and wind direction.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

A halo consisting of a faint white circle passing through the Sun and running parallel to the horizon for as much as 360

Precipitation caused by the ascent of moist air over an orographic barrier such as a Mountain range.

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

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

Same as marine rainbow.

The upper surface of a column of liquid.

Any twelve-month period, usually selected to begin and end during a relative dry season. Used a basis for processing streamflow and other hydrologic data. The period from October 1 to September 30 is widely used in the U.S.