The difference between the air temperature and the dew-point. Also called dew-point deficit, dew-point depression.

Same as Aeolian.

The actual time during which physical events take place.

Automated Surface Observing System. A network of instrumented weather stations deployed primarily by the National Weather Service to make weather observations without operator involvement.

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

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 ...

The writing component of a recording instrument.

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

The actual lifting force of an inflated balloon, usually expressed in grams.

The amount of moisture which, if available, would be removed from a given land area by evapotranspiration. Expressed in units of water depth.

Any device or instrument for measuring salinity, especially one based on electrical conductivity methods.

A unit that represents one degree of deviation from a reference point in the mean daily outdoor temperature (usually 65

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

See foehn.

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.

A semiconductor which exhibits rapid and extremely large changes in resistance for relatively small changes in temperature.

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

See captive balloon, ceiling balloon, constant-level balloon, free balloon, hurricane beacon, kytoon, Moby Dick balloon, pilot balloon, radiosonde balloon, rockoon, skyhook balloon, transosonde.

An instrument for taking photographs of an image of the sun in monochromatic light.