A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.

A constant which describes the performance of a wind vane in response to a step change in wind direction. It is calculated from the relative amount of overshoot on two successive swings (half cycles) of a decaying oscillation. This specification is dimens ...

The total amount of water transferred to the atmosphere by evapotranspiration.

A type of hygrometer which measures the water vapor content of the atmosphere by means of the absorption of vapor by a hygroscopic chemical.

An instrument for measuring the pressure of gases and vapors. A mercury barometer is a type of manometer.

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

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

A water-temperature thermometer provided with an insulated container around the bulb. It is lowered into the sea on a line until it has had time to reach the temperature of the surface water, then withdrawn and read. The insulated water surrounding the bu ...

The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air. Obtained by evaporation of water (or ice) from the muslin wick. Used in computing dew point and relative humidity.

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

A unit of luminance (or brightness) equal to 1/6 candles per square centimeter.

A common type of liquid-inglass thermometer, used, in meteorology, in psychrometers and as a maximum thermometer.

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 systematic observational error due to the characteristics of the observer. The uncertainty in a reading made by an observer may be acertained by a statistical analysis of his or her readings.

The actual lifting force of an inflated balloon, usually expressed in grams.

A unit of mass numerically equal to the molecular weight of the substance. The gram-mote or gram-molecule is the mass in grams numerically equal to the molecular weight, i.e. a gram-mole of oxygen is 32 grams.

Generic term for rapid variations in apparent position, brightness, or color of a distant luminous. object viewed through the atmosphere.

The height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified as "thin" or "partial." The ceiling is termed unlimited when these conditions are not satisfied. ...

A colloquial term in western Australia for a squall, associated with thunder, on the northwest coast in summer.

A method of upper air observation consisting of an evaluation of the wind speed and direction, temperature, pressure, and humidity aloft by means of a balloon-borne radiosonde tracked by radar or a radio theodolite.