See wind vane.

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.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

meter-An instrument for measuring the transmissivity of the atmosphere; a type of transmissometer. It consists of a constant- intensity collimated light source located at a suitable distance from a photoelectric cell. Variation in the turbidity of the atm ...

An instrument which measures the intensity of radiation by determining the amount of chemical change( or fluorescence produced by that radiation.

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

In meteorology, a deflecting force acting on a body in motion and resulting from the earth's rotation. It deflects air currents to the right in the northern hemisphere and to the left in the southern hemisphere, thus having an effect on wind direction.

An instrument for measuring the difference between incoming and outgoing terrestrial radiation.

A pyrheliometer of the bimetallic type used to measure the intensity of direct solar radiation.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

A pyranometer developed by M. Robitzsch. Its design utilizes three bimetallic strips which are exposed horizontally at the center of a hemispherical glass bowl. The outer strips are white reflectors and the center strip is a blackened absorber. The bimeta ...

Same as atmospheric pressure.

The temperature at which the liquid and solid forms of a substance may exist in equilibrium at a given pressure (usually one standard atmosphere). The true freezing point of water is known as the ice point.

The audio-frequency signal transmitted by the Diamond-Hinman radiosonde when the baroswitch pen passes each fifth contact of the commutator up to a number determined by the design of the commutator. It then signals every contact except the fifth, which is ...

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

An instrument that shows changes in humidity.