The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec2. Commonly used in gravimetry.

The combined processes by which water is transferred from the earth's surface to the atmosphere: evaporation of liquid or solid water plus transpiration from plants.

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

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.

A rotation anemometer in which the axis of rotation is horizontal. The instrument has either flat vanes (as in the air meter) or helicoidal vanes (as in the propeller anemometer). The relation between wind speed and angular rotation is almost linear.

The process by which small particles suspended in a medium of a different refractive index diffuse a portion of the incident radiation in all directions. In scattering no energy transformation results, only a change in the spatial distribution of the radi ...

See calorie.

Eluding precise prediction, completely irregular.

A cone-tipped metal rod designed to be driven downward into deposited snow or firn. The measured amount of force required to drive the rod a given distance is an indication of the physical properties of the snow or firn.

Same as atmospheric pressure.

A protective coating applied to circuits.

In general, solar radiation received at the earth's surface. Contracted from incoming solar radiation.

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

The physical exposure of an instrument. The effect of immediate environment upon the representativeness of the measurements obtained by meteorological instruments is considerable and not always correctable. The purpose of the instrument shelter is to prov ...

An instrument for measuring the difference of the solar radiation falling on both sides of a horizontal surface from the whole hemisphere.

A polarimeter utilizing a Wollaston prism as a polarizer and a Nicol prism as an analyzer.

The ratio of the output of an instrument to the input value, i.e. a rain gauge with a sensitivity of 1 tip per 0.01"

The probability distribution of random errors, typically a normal distribution with a zero mean.

Emission or transfer of energy in the form of electromagnetic waves or particles.