A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

A device for measuring the frequency of occurrence of atmospherics whose intensity is greater than a predetermined level.

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

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 ...

A device for measuring sea-surface waves. It consists of a weighted pole below which a disk is suspended at a depth sufficiently deep for the wave motion associated with deepwater waves to be negligible. The pole will then remain nearly as if anchored to ...

Situated on the side from which the wind blows.

See feed.

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

Air in motion relative to the surface of the earth. Almost exclusively used to denote the horizontal component.

The atmospheric pressure at mean sea level either directly measured by stations at sea level or empirically determined from the station pressure and temperature by stations not at sea level. Used as a common reference for analyses of surface pressure patt ...

The height of the cloud base above the local terrain.

A instrument designed to study small fluctuations of some quantity. The microbarograph is an example of a recording pressure variometer.

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

General name for an instrument which measures the earth's magnetic field intensity.

A large body of air having similar horizontal temperature and moisture characteristics.

A very sensitive electrostatic electrometer for measuring small potential differences.

Same as windsock.

Abbreviation for Instrument Flight Rules, but commonly used to refer to the weather and/or flight conditions to which these rules apply, i.e. low visibility.

Any sudden and heavy rain, almost always of the shower type.

See radiosonde commutator.