A basic equation in night visual range theory, relating the illuminance of a point source of light to distance and the transmissivity of the atmosphere.

The writing component of a recording instrument.

The rate of decrease of pressure per unit distance at a fixed time.

An ice coating with a consistency intermediate between glaze and rime.

Part of a computer word that has meaning in itself, often, a byte.

The record made by a hygrograph.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.

The flux of visible radiation, so weighted as to account for the manner in which the response of the human eye varies with the Wavelength of radiation. The basic unit for luminous flux is the lumen,

Random Access Memory. The memory of a computer which can be read and written into at any location without passing through preceding locations.

An instrument for measuring the ultraviolet in solar and sky radiation.

The process by which events in the real world are translated into machine-readable signals.

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

The rate of decrease of temperature with height when unsaturated air is lifted adiabatically (without exchange of heat with its surroundings). The decrease is due to expansion as the air is lifted to a lower pressure.

Companion to the wet-bulb thermometer in a psychrometer. Used to measure ambient air temperature.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

A type of cloud height indicator which uses a searchlight to project vertically a narrow beam of light onto the cloud base. The height of the cloud is determined using a clinometer, located at a known distance from the ceiling light, to measure the angle ...

Same as atmometer.

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

An instrument for measuring the extinction coefficient in water.

An instrument designed to measure quantities of heat. Sometimes used in meteorology to measure solar radiation.