A small balloon, loaded with ballast and inflated so that it will explode at a predetermined altitude, which is attached to a larger balloon.

Thermometer in which the difference in the rates of expansion with temperature of a liquid and its receptacle is used as a measure of the temperature. The liquid used may be ethyl alcohol, toluene, petroleum, or mercury.

Wind with a speed between 4 and 27 knots (4 and 31 mph); Beaufort scale numbers 2 through 6.

An estimate of the temperature of an incandescent body, determined by observing the wavelength at which it is emitting with peak intensity (its color) and using that wavelength in Wien's law.

Any source of radiant energy, especially electromagnetic energy.

Same as mirror nephoscope.

The portion of the precipitation on the land which ultimately reaches the streams. especially the water from rain or melted snow that flows over the surface.

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

Companion to the wet-bulb thermometer in a psychrometer. Used to measure ambient air temperature.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

A self-recording instrument used on aircraft for the simultaneous recording of atmospheric pressure, temperature, and humidity.

The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air. Obtained by evaporation of water (or ice) from the muslin wick. Used in computing dew point and relative humidity.

See radiosonde commutator.

In general, any self-recording instrument carried aloft by any means to obtain meteorological data.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

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

See evaporation pan.

An ice coating with a consistency intermediate between glaze and rime.

Same as rain gauge.

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