The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.

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. ...

General name for a type of instrument which measures the inclination of the wind to the horizontal plane. See bivane.

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

An instrument, located at the surface observing station, which is used to record the data presented by a radiosonde aloft.

The general term for anemometers operating on the principle that the heat transfer to air from an object at an elevated temperature is a function of the air speed. Examples are the hot-wire anemometer and the katathermometer.

A wind vane used to obtain the horizontal and vertical components of the wind.

For a given cloud or cloud laver. the lowest level in the atmosphere at which the air contains a perceptible quantity of cloud particles.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

An instrument for collecting liquid water from the atmosphere.

An instrument for the measurement of both solar and terrestrial radiation.

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

An area of low atmospheric pressure which has a closed circulation that is cyclonic (counterclockwise in northern hemisphere and clockwise in southern hemisphere).

A subtle, diumal component of the wind velocity leading to a diumal shift of the wind or turning of the wind with the sun, produced bv the east-to-west progression of daytime surface heating.

The amount of precipitation captured by a rain gauge.

Formation of a single water drop by the union of two or more colliding drops.

Automated Surface Observing System. A network of instrumented weather stations deployed primarily by the National Weather Service to make weather observations without operator involvement.

A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

Same as atmometer.

American Standard Code for Information Interchange. A standard code used to represent data using 8 bits (7 data bits and I parity bit) per character.