The state of the atmosphere, mainly with respect to its effects upon life and human activities. As distinguished from climate, weather consists of the short-term (minutes to months) variations of the atmosphere.

A wind vane used to obtain the horizontal and vertical components of the wind.

Same as dropsonde.

See approximate absolute temperature scale, Celsius temperature scale, centigrade temperature scale, Fahrenheit temperature scale, Kelvin temperature scale, Rankine temperature scale, Reaumur temperature scale,

See calorie.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

Rate of flow of water past a point in a stream, expressed as volume per unit time, i.e. cubic feet per second.

A pressure-operated switching device used in a radiosonde. In operation, the expansion of an aneroid capsule causes an electrical contact to scan a radiosonde commutator composed of conductors separated by insulators.

The line-of-sight distance between two objects.

In folklore, a name for wind.

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

Rate of wind movement in distance per unit time.

A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.

Liquid water at temperatures colder than freezing.

A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.

An instrument designed to measure the effect of sunlight on evaporation from plant foliage. It consists of a porous clay atmometer whose surface has been blackened so that it absorbs radiant energy.

An instrument which indicates the presence of precipitation. The ombroscope consists of a heated, water-sensitive surface which indicates by mechanical or electrical techniques the occurrence of precipitation.

The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec2. Commonly used in gravimetry.

See photometer.

Same as precipitation- effectiveness index.