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.

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.

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

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.

Particle on which the freezing of water occurs.

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

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

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 feeble oscillatory disturbance of the earth's crust, detectable only by very sensitive seismographs. Certain types of microseisms seem to be closely correlated with pressure disturbances. See microbarm.

Same as Aeolian.

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.

An instrument for measuring the frost point of the atmosphere.

Of or pertaining to rain.

Thermodynamic change of state of a system in which there is transfer of heat across the boundaries of the system. Compare to adiabatic process.

Root Mean Square. This notation is used frequently with error analysis. In that context, it is the square root of the arithmetic mean of the squares of the deviations of the individual calibration points from the theoretical or ideal response.

The outer, solid portion of the earth: the crust of the earth.

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

A technique for making winds aloft observations in which two theodolites located at either end of a baseline follow the ascent of a pilot balloon. Synchronous measurements of the elevation and azimuth angles of the balloon. taken at periodic intervals, pe ...

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.

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 ...