A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

A reversing thermometer (for seawater temperature) which is not protected against hydrostatic pressure. The mercury bulb is therefore squeezed, and the amount of mercury broken off on reversal is a function of both temperature and of hydrostatic pressure.

A relatively small-scale, upward moving current of air.

A numbering system using a base number of 2 and having only two digits: 0 and 1. The fundamental system of representing information with electrical pulses.

In folklore, a name for rain.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

A protective coating applied to circuits.

A buoyant balloon kept from rising freely by means of a line secured to a point on the ground, as opposed to a free balloon. See kytoon.

An instrument for the measurement of both solar and terrestrial radiation.

The maximum difference in output for any given input (within the specified range) when the value is approached first with increasing, and then with decreasing, input signals. Caused by energy absorption in the elements of the measuring instrument. Usually ...

An instrument whose calibration is determined by comparison with an absolute instrument.

A barometer which measures atmospheric pressure using one or a series of aneroid capsules. Also called holosteric barometer.

The record obtained from a bolometer.

Same as constant-level balloon.

The correction applied to an instrument to account for the effect of temperature upon its response characteristics.

Infrared radiation emitted by or being propagated through the atmosphere.

A definite portion of a stream channel, commonly taken between two gauging stations, but may be taken between any two specified points.

The value of atmospheric pressure to which the scale of a pressure altimeter is set so as to indicate airport elevation. The altimeter setting is included as part of an aviation weather observation.