Rain gauge which registers precipitation that is too light to be registered by ordinary recording of the depth of water from precipitation. Same as ombrometer.

The length of air flow past a wind vane required for the vane to respond to 50 percent of a step change in wind direction. Expressed in feet or meters and calculated from delay time times wind tunnel speed.

Wind with a speed between 17 and 21 knots (19 and 24 mph); Beaufort scale number 5.

That portion of the record of a microbarograph between any two (or a specified small number) of successive crossings of the average pressure level (in the same direction). Analogous to microseism.

A measure of the intrinsic luminous intensity emitted by a source in a given direction. Luminance is a measure only of light. The comparable term for electromagnetic radiation in general is radiance.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

The value of the quantity measured, as indicated or otherwise provided by a measuring instrument.

The temperature to which a sample of air must be cooled, while the mixing ratio and barometric pressure remain constant, in order to attain saturation by water vapor. When this temperature is below O

Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day.

A fixed support for mounting maximum and minimum thermometers of the liquid-in-glass type. The support holds the thermometers at the correct operating attitude and also permits their rotation for resetting when desired.

For a given location, a measure of the long-range effectiveness of precipitation in promoting plant growth. Also called precipitation-evaporation index.

Thermometer in which the difference in the rates of expansion with temperature of a liquid and its receptacle is used as a measure of the temperature. The liquid used may be ethyl alcohol, toluene, petroleum, or mercury.

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

A small, limited-capacity central processing unit contained entirely on one semiconductor chip.

The change in barometric pressure within a specified period of time (typically 3 hours for meteorological observations).

A set of weekly colored rainbow arcs sometimes discernable inside a primary rainbow.

Radiation coming from the solid angle of the sun's disc, as opposed to diffuse sky radiation, effective terrestrial radiation, or radiation from any other source. Direct solar radiation is measured by pyrheliometers.

Particle on which the freezing of water occurs.

An instrument for measuring the frost point of the atmosphere.

An elongated area of relatively high pressure. Usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow. The opposite of a trough.