That part of snow melt that reaches stream channels as runoff.

A cylinder installed in a body of water or an evaporation pan to hold a sensor, such as a float to measure water level or a hook gage. The stillwell is constructed so that there is free movement of water in and out of it, and it therefore provides a repre ...

Anemometer whicb measures wind speed by measuring the degree of cooling of a metal wire heated by an electric current. A type of cooling power anemometer.

A measure of long-term precipitation effectiveness. The ratio of the normal annual rainfall to the normal annual evaporation.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

The elevation of the water surface in a stream as measured by a river gauge with reference to some arbitrarily selected zero datum.

Thermometer for measuring the temperature in the soil at different depths.

A reversing thermometer (for seawater temperature) which is not protected against hydrostatic pressure. The mercury bulb is therefore squeezed, and the amount of mercury broken off on reversal is a function of both temperature and of hydrostatic pressure.

The stage on a fixed river gauge at which it is necessary to begin issuing warnings or river forecasts if adequate precautionary measures are to be taken before flood stage is reached.

A general term for atmospheric water in any of its forms, i.e. clouds, fog, hail, ice crystals, rain.

A term used to describe a sensor (or sensors), the associated transducer(s), and the data readout or recording device.

An aneroid barograph designed to record atmospheric pressure variations of very small magnitude.

An anemometer which measures wind speed in terms of the drag which the wind exerts on a solid body. See bridled-cup anemometer, normal-plate anemometer, pendulum anemometer.

A particular pattern of snow sampler having an internal diameter of 1.485 inches so that each inch of water in the sample weighs one ounce.

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

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

Very generally, any moving- stream of air. It has no particular technical connotation.

See calorie.

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.