A faintly-colored circular arc similar to a rainbow but formed on fog layers containing drops whose diameters are 100 microns or less. Also called mistbow, white rainbow.

The volume of liquid water evaporated per unit area in unit time. usually measured as the depth of liquid water lost per unit time from the whole area.

A conically shaped, copper rain gauge shield.

An addition to a rawinsonde system which allows determination of the slant range to the radiosonde.

A halo phenomenon consisting of a horizontal circle passing through the moon, corresponding to the parhelic circle through the sun. Produced by reflection of moonlight from ice crystals.

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.

The humidity transducinu element in a Diamond-Hinman radiosonde. Also called electrolytic strip.

An instrument which measures the transmissivity of the atmosphere between two points for the determination of visual range.

A hygrometer which uses a transducing element whose electrical properties are a function of atmospheric water vapor content. The humidity strip and carbon-film hygrometer element are examples of such a transducer.

A mercury barometer in which the lower mercury surface is larger in area than the upper surface. The basic construction of a cistern barometer is as follows: A glass tube one meter in length, sealed at one end is filled with mercury, and then inverted. Th ...

Same as fogbow.

A device attached to a meteorological instrument to provide ventilation; usually a suction fan.

A mercury-in-glass thermometer which records the temperature upon being inverted and retains its reading until being returned to the first position.

A radiosonde whose carrier wave is modulated by audio-frequency signals whose frequency is controlled by the sensing elements of the instrument.

The upward force produced by the gas in a balloon. It is equal to the free lift plus the weight of the balloon and the attached equipment.

The difference between downward and upward (total) radiation; net flux of all radiation.

A modification of the dew cell used in radiosonde equipment.

An instrument for measuring differences in electric potential.

A contact anemometer connected to an electrical circuit which is so arranged that the average wind speed is indicated.

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