An instrument which measures the instantaneous rate at which rain is falling on a given surface. Also called a rate-of-rainfall gauge.

The maximum distance, usually horizontally, at which a given object or light source is just visible under particular conditions of transmittance and background luminance.

An early and once universal name for the mercury barometer.

Same as precipitation-evaporation ratio.

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

In a radiosonde observation, a level (other than a standard level) for which values of pressure, temperature, and humidity are reported because temperature and/or humidity data at that level is sufficiently important or unusual to warrant the attention of ...

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

Same as rain-intensity gauge.

The record made by a hygrograph.

See bimetallic thermometer.

Thermometer used for measuring the highest temperature attained during a given interval of time, for example, a day.

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

Occupational Safety and Health Administration. A regulatory office of the U.S. Department of Labor.

The process by which events in the real world are translated into machine-readable signals.

A relatively small-scale, upward moving current of air.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

Frequency Shift Keying. A form of frequency modulation of a data signal performed by a modem for transmission over dedicated wire or phone lines.

An anemometer which measures wind speed in terms of the drag which the wind exerts on a solid body. See bridled-cup anemometer, normal-plate anemometer, pendulum anemometer.

The temperature at which all three phases of a substance can exist in equilibrium. This temperature occurs at only one pressure. The triple-point of water is 273.16 K and is the basis of the Kelvin scale.