An instrument which measures combined direct solar radiation and diffuse sky radiation. See pyrheliometer, Robitzsch actinograph. solarimeter. See also albedometer.

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

Particle on which the freezing of water occurs.

A protocol similar to RS232 which permits data interchange on multidrop networks of up to 32 nodes using a single twisted pair cable. In order for this protocol to be used, each device on a network must have some level of intelligence in order establish o ...

Operation mode of a communication circuit in which each end can transmit and receive, but not simultaneously.

Downward scattered and reflected solar radiation, coming from the whole hemisphere with the exception of the solid angle of the sun's disc on a surface perpendicular to the axis of this cone.

An atmometer which uses a filter paper disc as the evaporating element. The amount of water evaporated through the paper is read at the graduated tube reservoir.

A feeble oscillatory disturbance of the earth's crust, detectable only by very sensitive seismographs. Certain types of microseisms seem to be closely correlated with pressure disturbances. See microbarm.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

A general term for instruments designed to measure the amount of cloudiness.

The cardinal points of the compass, i.e. north, south, east, west.

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

American Standard Code for Information Interchange. A standard code used to represent data using 8 bits (7 data bits and I parity bit) per character.

Apparatus from which the nature and time of precipitation may be determined.

A motorlike device containing a rotor and a stator and capable of converting an angular position into an electrical signal, or an electrical signal into an angular position. When several synchros are correctly connected, all of the rotors will align thems ...

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

The atmospheric pressure at the level of the barometer. May or may not be the same as station pressure.

See calorie.

The maximum distance along the runway at which the runway lights are visible to a pilot at touchdown. Runway visual range may be determined by an observer located at the end of the runway, facing in the direction of landing, or by means of a transmissomet ...