Old snow that has become granular and compacted as a result of melting and refreezing.

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

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.

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

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

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. ...

Same as atmometer.

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.

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

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.

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.

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

A protective coating applied to circuits.

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.

A general term for instruments designed to measure the speed or force 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 collecting liquid water from the atmosphere.