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

A line drawn through geographical points having the same duration of sunshine (or other function of solar radiation) during a given interval of time.

A constant which describes the performance of a wind vane in response to a step change in wind direction. It is calculated from the relative amount of overshoot on two successive swings (half cycles) of a decaying oscillation. This specification is dimens ...

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

A direct-vision nephoscope constructed in the following manner: A grid-work of bars is mounted horizontally on the end of a vertical column and made free to rotate about the vertical axis. The observer rotates the grid and adjusts his or her position unti ...

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

Same as luminous intensity.

check chamber-A chamber use to check the sensing elements of radiosonde equipment.

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

Forecasting weather by the use of numerical models, run on high speed computers. Most of the NWP for the National Weather Service is done at the National Centers for Environmental Prediction (NCEP).

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

A fixed-length group of bits representing the large data element handled as a unit by a computer. Word length is determined by the capacity of the CPU registers.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

The upper surface of a column of liquid.

A rainbow formed by light rays which have been reflected from an extended water surface. Not to be confused with a reflected rainbow whose image may be seen in a still body of water. The center of a reflection rainbow is at the same elevation as the sun b ...

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

A colloquial term in western Australia for a squall, associated with thunder, on the northwest coast in summer.

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

The total luminous flux received on a unit area of a given real or imaginary surface, expressed in such units as the foot-candle, lux, or phot.

The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.