Water condensed onto objects at or near the ground, due to the fact that their temperatures have fallen below the dew point temperature of the surrounding air, but not below freezing.

An instrument for studying, or examining substances in, polarized light. See Savant polariscope.

Anemometer which measures wind speed by measuring the degree of cooling of a metal film heated by an electric current. A type of cooling-power anemometer.

An absolute temperature scale with the ice point of pure water defined as 273.16 K. The size of the degree is the same as on the Celsius scale, and the zero point is absolute zero.

Interational thermometric scale on which the freezing point of water equals 0

Old snow that has become granular and compacted as a result of melting and refreezing.

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

An instrument which measures the rate of evapotranspiration. It consists of a vegetation soil tank so designed that all water added to the tank and all water left after evapotranspiration can be measured.

A form of data transmission in which the bits of each character are all sent simultaneously, resulting in extremely fast communication but requiring a communication path for each bit. Compare to serial data transmission.

Same as fogbow.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

An instrument for the measurement of the radon content of the atmosphere.

Programmable Read-Only Memory. Read-only memory which can be programmed by the user using a special hardware programmer.

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

The direction from which the wind is blowing, measured in points of the compass or in azimuth degrees.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

A device for measuring the height of tide. It may be simply a graduated staff in a sheltered location where visual observations can be made, or it may consist of an elaborate recording instrument (sometimes called a marigraph) making a continuous graphic ...

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

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.