A protocol similar to RS232 which makes use of differential transmission to provide high speed data transmission over significantly longer distances.

Wind with a speed below 1 knot (1 mph); Beaufort scale number 0.

A polariscope consisting of a specially constructed double plate polarizer and a tourmaline plate analyzer. Polarized light passing through the instrument is indicated by the presence of parallel colored fringes, while unpolarized light results in a unifo ...

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

An instrument resulting from the combination of a thermograph and a hygrograph and furnishing, on the same chart, simultaneous time recording of ambient temperature and humidity.

A rain gauge which automatically records the amount of precipitation collected, as a function of time.

An ion counter of the aspiration condenser type, used for the measurement of the concentration and mobility of small ions in the atmosphere.

A hypothetical, ideal body which absorbs completely all incident radiation. independent of wavelength and direction. No actual substance behaves as a true black body, although platinum black and other soots rather closely approximate this ideal. However, ...

The array of indicating marks and figure in relation to which the position of an index is observed, i.e. a scale plate on a recorder.

A reversing thermometer (for seawater temperature) which is not protected against hydrostatic pressure. The mercury bulb is therefore squeezed, and the amount of mercury broken off on reversal is a function of both temperature and of hydrostatic pressure.

Any source of radiant energy, especially electromagnetic energy.

Apparatus designed to measure and record the size distribution of raindrops as they occur in the atmosphere.

General term for an instrument which records the vertical electric current in the atmosphere.

Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

The average temperature of the air as indicated by a properly exposed thermometer for a given time period, usually a day, a month, or a year.

Precipitation falling from a cloud, usually in wisps or streaks, but evaporating before it reaches the ground.

Capacity of a soil or other surface to be penetrated by water sinking into the ground under the force of gravity. It thus expresses the rate of percolation.

A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

A systematic observational error due to the characteristics of the observer. The uncertainty in a reading made by an observer may be acertained by a statistical analysis of his or her readings.