An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

A device for measuring sea-surface waves. It consists of a weighted pole below which a disk is suspended at a depth sufficiently deep for the wave motion associated with deepwater waves to be negligible. The pole will then remain nearly as if anchored to ...

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

Same as an upper air observation, but commonly used to refer to a single complete radiosonde observation.

A small anemometer with flat vanes which indicates the number of linear feet or meters of air which have passed the instrument during its exposure.

Technically, the temperature registered by the dry-bulb thermometer of a psychrometer. However, it is identical with the temperature of the air and may also be used in that sense.

A common type of terrestrial scintillation; shimmering over a hot surface (such as a roadway) on a quiet, cloudless. summer day.

A type of precipitation composed of unbranched crystals in the form of needles, columns, or plates. Usually has a very slight downward motion and may fall from a cloudless sky.

See radar theodolite, radio direction-finder.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

An old nautical term for mercury barometer.

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

A device, similar to a potometer, for measuring transpiration, consisting of a vessel containing soil in which one or more plants are rooted and sealed so that water can escape only by transpiration from the plant.

A hygrometer based upon the diffusion of water vapor through a porous membrane.

A mercury barometer in which the tube is U-shaped and the upper and lower mercury surfaces have the same diameter.

Name sometimes given to a transmissometer.

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

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.

A systematic summary of the terms (inflow, outflow, and storage) of the storage equation as applied to the computation of soil-moisture changes, ground-water changes, etc. An evaluation of the hydrologic balance of an area. Also called basin accounting, w ...