An instrument for measuring differences in electric potential.

A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

An instrument which measures the instantaneous rate at which rain is falling on a given surface. Also called a rate-of-rainfall gauge.

A numbering system using a base number of 16 and including the ten decimal digits (0 to 9) along with six alpha digits (A to F). Thus. a digit is available to represent each of the possible values of a 4-bit binary digit.

A unit of energy per unit area commonly employed in radiation theory. Equal to one gram-calorie per square centimeter.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

Very generally, any moving- stream of air. It has no particular technical connotation.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

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.

A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

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

The distance or length of flow of the air past a point during a given interval of time.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

A thermopile used in some types of radiation instruments. See solarimeter.

A clay atmometer consisting of a hollow ceramic sphere through which evaporation occurs. Evaporation is measured by the loss of water from the reservoir which feeds the sphere.

See stage.

A graduated scale placed in a position so that the stage of a stream may be read directly from it. Staff gauges may be placed on bridge piers or pilings, etc., or placed on specially constructed supports.

A recording magnetometer.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.