A unit of luminance or brightness equal to 1/d candles per foot'.

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

A class of instruments employed to determine the electric potential at a point in the atmosphere, and ultimately the atmospheric electric field.

A modification of the dew cell used in radiosonde equipment.

An instrument for determining the degree of polarization of light. See photopolarimeter.

Any meteorological instrument, such as a radiosonde, in which the recording apparatus is located at some distance from the measuring apparatus.

A recording pressure-tube anemometer in which the wind scale of the float manometer has been made linear by the use of springs, i.e. Dines anemometer.

The difference between downward and upward (total) radiation; net flux of all radiation.

The number of cycles per second between the limits of a frequency band.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

A unit of power equal to one joule per second or 10' ergs per second.

A small balloon whose ascent is followed by a theodolite in order to obtain data for the computation of winds aloft.

The maximum difference in output for any given input (within the specified range) when the value is approached first with increasing, and then with decreasing, input signals. Caused by energy absorption in the elements of the measuring instrument. Usually ...

Facing away from the wind.

Clouds which cover between 6/10 and 9/10 of the sky. See Sky Terminology.

An Instrument used to determine dew point.

The difference between the air temperature and the dew-point. Also called dew-point deficit, dew-point depression.

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 device for computing certain psychrometric data, usually the dew point and the relative humidity, from known values of the dry-bulb and wet-bulb temperatures and the atmospheric pressure. One type is the circular slide-rule form and, like the psychromet ...

The height ascribed to the lowest layer of clouds or obscuring phenomena when it is reported as broken, overcast, or obscuration and not classified as "thin" or "partial." The ceiling is termed unlimited when these conditions are not satisfied. ...