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 for obtaining a continuous record of stage at a point on a stream. The most common recorders consist of a float-actuated pen which traces a record on a clock driven chart.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

Strong winds concentrated within a narrow band in the atmosphere. The jet stream often "steers" surface features such as front and low pressure systems.

Literally "not wet", containing no liquid.

A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

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. ...

The true freezing point of water. The temperature at which a mixture of air-saturated pure water and pure ice may exist in equilibrium at a pressure of one standard atmosphere.

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

Same as atmometer.

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

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 unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

Complementary Metal-Oxide Semiconductor. A method of making silicon chips that results in low power consumption by the circuits.

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

An instrument for collecting liquid water from the atmosphere.

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

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

A protective coating applied to circuits.

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