A combination cup anemometer and pressure-plate anemometer, consisting of an array of cups about a vertical axis of rotation, the free rotation of which is restricted by a suitable spring arrangement.

An instrument used to indicate wind direction.

The difference between temperature measurements taken at two significant levels above the ground. Temperatures at 10 and 40 meters are commonly used.

Solar and terrestrial radiation directed upward (away From the earth's surface); outgoing radiation.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

Interational thermometric scale on which the freezing point of water equals 0

General term for an instrument which records the vertical electric current in the atmosphere.

An approximation to the complete equations describing atmospheric motion in which only the terms most important for the growth and decay of synoptic scale extratropical weather systems (i.e., the large areas of high and low pressure seen on weather maps) ...

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.

A thermograph in which ventilation is provided by a suction fan.

Same as mirror nephoscope.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

A hygrometer which uses a transducing element whose electrical properties are a function of atmospheric water vapor content. The humidity strip and carbon-film hygrometer element are examples of such a transducer.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

The ratio of the amount of electromagnetic radiation reflected by a body to the amount incipient upon it, commonly expressed as a percentage. The albedo is to be distinguished from the reflectivity, which refers to one specific wavelength.

A general term for instruments designed to measure the amount of cloudiness.

National Weather Service. Administered by the U.S. Department of Commerce.

Same as contact anemometer.

One of the radiation laws which states that the wavelength of maximum radiation intensity for a black body is inversely proportional to the absolute temperature of the radiating black body.