A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

An instrument for determining the degree of polarization of light. See photopolarimeter.

See hydrologic accounting.

film hygrometer element-An electrical hygrometer element constructed of a plastic strip coated with a film of carbon black dispersed in a hygroscopic binder. Variations in atmospheric moisture content vary the volume of the binder and thus change the resi ...

In a system of moist air, the dimensionless ratio of the mass of water vapor to the total mass of the system.

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

General name for an instrument which measures the earth's magnetic field intensity.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

The record made by a hygrograph.

An instrument which automatically records the measurement of two or more meteorological elements.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

Same as recording rain gauge.

A type of cloud height indicator which uses a searchlight to project vertically a narrow beam of light onto the cloud base. The height of the cloud is determined using a clinometer, located at a known distance from the ceiling light, to measure the angle ...

A wind scale adapted by the U.S. Forest Service for use in the forested areas of the northern Rocky Mountains (NRM). It is an adaptation of the Beaufort wind scale. The difference between these two scales lies in the specification of the visual effects of ...

See hurricane beacon.

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

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

Name sometimes used in place of pyranometer as a generic term.

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.