An instrument for measuring snow hardness in terms of the resistance of snow to the pressure exerted by a disk attached to a spring-loaded rod, a gauge calibrated in pounds per square inch registers the amount of resistance. See Canadian hardness gauge.

A synoptic code approved by the World Meteorological Organization in which the observable meteorological elements are encoded and transmitted in "words" of five numerical digits length. Often abbreviated synoptic code.

A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

A type of electrical thermometer in which the thermal element is a substance whose electrical resistance varies with the temperature. Such thermometers can be made with very short time constants and are capable of highly accurate measurements.

An effect noted primarily in wet snow conditions when snow clings to the sides of a precipitation gauge and gradually accumulates until the gauge orifice is capped with accumulated snow. This effect can be minimized by using large collectors, and wind scr ...

A device for measuring the river stage. Also called stream gauge.

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

A thermopile used in some types of radiation instruments. See solarimeter.

A device, similar to a phytometer, for measuring transpiration. It consists of a small vessel containing water and sealed so that the only escape of moisture is by transpiration from a leaf, twig, or small plant with its cut end inserted in the water.

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

A line of equal or constant temperature.

See photometer.

That stage, on a fixed river gauge, at which overflow of the natural banks of the stream begins to cause damage in any portion of the reach for which the gauge is used as an index.

A hygrometer in which the rotation of the hygrometric element is a function of humidity.

A magnetometer of the electromagnetic type which is used to measure the horizontal intensity of the earth's magnetic field.

The total amount of water transferred to the atmosphere by evapotranspiration.

Winds which, over a small area, differ from those which would be appropriate to the general pressure distribution.

A graphical representation of stage or discharge at a point on a stream as a function of time.

A type of modulation in which the frequency of a continuous radio carrier wave is varied in accordance with the properties of a second (modulating) wave.

A device for computing certain psychrometric data, usually the dew point and the relative humidity, from known values of the dry-bulb and wet-bulb temperatures and the atmospheric pressure. One type is the circular slide-rule form and, like the psychromet ...