Instrument used to measure the amount of water evaporated from the soil surface during a given time interval.

Same as atmometer.

Same as river gauge.

A unit of power equal to one joule per second or 10' ergs per second.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

Balance of the water resources of a region, comparing precipitation and inflow with outflow, evaporation, and accumulation.

An instrument for taking photographs of an image of the sun in monochromatic light.

The rate of decrease of temperature with height when unsaturated air is lifted adiabatically (without exchange of heat with its surroundings). The decrease is due to expansion as the air is lifted to a lower pressure.

An instrument designed to measure the effect of sunlight on evaporation from plant foliage. It consists of a porous clay atmometer whose surface has been blackened so that it absorbs radiant energy.

Radiation with wavelengths less than 4 microns.

Programmable Read-Only Memory. Read-only memory which can be programmed by the user using a special hardware programmer.

An instrument for measuring differences of electric potential.

See bimetallic thermometer.

Central Processing Unit. The part of a computer which controls and directs all functions.

Downward-facing pyranometer used for measuring reflected solar radiation.

A conically shaped, copper rain gauge shield.

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.

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

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.