The smallest change in the environment that causes detectable change in the indication of an instrument. Compare to sensitivity.

Wind with a speed between 56 and 63 knots (64 and 72 mph); Beaufort scale number 11.

Precipitation composed of liquid water drops more than 0.5 mm in diameter, failing in relatively straight, but not necessarily vertical, paths. Compare to drizzle.

The difference between the input quantity applied to a measuring instrument and the output quantity indicated by the instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

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

The temperature registered by a thermometer with its bulb at the level of the tops of the grass blades in short turf.

A modification of the dew cell used in radiosonde equipment.

A wind (or component thereof) directed down the slope of an incline and caused by greater air density near the slope than at the same levels some distance horizontally from the slope. Also called drainage wind and sometimes called katabatic wind.

A box-like structure designed to protect certain meteorological instruments from exposure to direct sunlight, precipitation, and condensation, while at the same time providing adequate ventilation. Instrument shelters are painted white, have louvered side ...

The succession of stages through which water passes on the ground and in the atmosphere: evaporation from land or bodies of water, condensation to form clouds, precipitation, accumulation in the soil or in bodies of water, and re-evaporation.

Same as fogbow.

A hydrometeor consisting of a visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface.

A form of psychrometer with wet-bulb and dry-bulb thermometers mounted on opposite sides of a specialty designed graph of the psychrometric tables. It is so arranged that the intersections of two curves determined by the wet-bulb and dry-bulb readings -yi ...

Negative Vorticity Advection.

The size of the area comprising a watershed or river basin. Also called catchment area.

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 ...

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

See hook gauge.

The total area drained by a river and its tributaries. Same as watershed.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.