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

A thermometer designed for use in measuring the temperature of sea water. One form consists of a mercury-in-glass thermometer protected by a perforated metal case. Another form consists of a mercury-in-glass thermometer surrounded by a metal case which fo ...

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

Electromagnetic radiation of very short wavelength. lying within the wavelength interval of 0.1 to 1.5 angstroms (between gamma rays and ultraviolet radiation). X-rays penetrate various thicknesses of all solids, and they act on photographic plates in the ...

A mercury barometer in which the tube is U-shaped and the upper and lower mercury surfaces have the same diameter.

A subtle, diumal component of the wind velocity leading to a diumal shift of the wind or turning of the wind with the sun, produced bv the east-to-west progression of daytime surface heating.

Line drawn through geographical points recording equal amounts of precipitation during a given time period or for a particular storm.

An instrument that shows changes in humidity.

A temperature-sensing element which converts thermal energy directly into electrical energy. In its basic form it consists of two dissimilar metallic conductors connected in a closed loop. Each junction forms a thermocouple. If one thermocouple is maintai ...

The decrease of an atmospheric variable with height, the variable being temperature, unless otherwise specified.

A hygrometer based upon the diffusion of water vapor through a porous membrane.

Anemometer which measures wind speed by the speed of rotation of 3 or 4 hemispherical or conical cups, each fixed to the end of a horizontal arm projecting from a vertical axis. See condenser-discharge anemometer, contact anemometer. Compare to bridled-cu ...

A precipitation gauge consisting of a receiver in the shape of a funnel which empties into a bucket mounted upon a weighing mechanism. The weight of the catch is recorded as inches of precipitation.

An instrument, for the recording of two or more meteorological parameters, in which the ventilation is provided by a suction fan.

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

The state of the weather with respect to its effect upon the kindling and spreading of forest fires.

The study of waters (including oceans, lakes, and rivers) embracing either: (a) their physical characteristics, from the standpoint of the oceanographer or limnologist; or (b) the elements affecting safe navigation, from the point of view of the mariner. ...

An instrument for taking photographs of an image of the sun in monochromatic light.

See bimetallic thermometer.

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