An instrument which measures the scattering function of particles suspended in a medium in order to determine the visual range through the medium. See visibility meter.

An instrument that shows changes in humidity.

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

A rotation anemometer which has a horizontal axis upon which helicoidal shaped vanes are mounted. See windmill anemometer.

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 line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.

A power supply which achieves its output regulation by means of one or more active power handling devices which are alternately placed in the "off" or "on" states. It is more efficient than linear supplies which vary the conduction of power devices to ach ...

Lowest altitude in the atmosphere over a given location at which the air temperature is 0

A line drawn through geographical points having the same pluvial index.

A general term for instruments designed to measure the speed or force of the wind.

See radiosonde commutator.

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.

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.

The change in a performance characteristic caused by a change in a specified operating condition from reference operating condition, all other conditions being held within the limits of reference operating conditions.

Same as freezing point.

A recording hair hygrometer.

The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

The gravity flow of water within soil.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.