Situated on the side from which the wind blows.

A thermometer consisting of a clock mechanism the speed of which is a function of temperature.

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 ...

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

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.

Same as windsock.

A clock-driven instrument mounting which automatically and continuously points in the direction of the sun. It is used with a pyrheliometera,hen continuous direct solar radiation measurements are required.

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 ...

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.

Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.

The height of the cloud base above the local terrain.

See calorie.

See radiosonde commutator.

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

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

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

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

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

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 ...

See feed.