A system of designating meteorological observing stations by number. established and administered by the World Meteorological Organization. Under this scheme, specified areas of the word are divided into "blocks" each bearing a two-number designator. Stat ...

Same as rain gauge.

Contraction for pilot balloon observation.

An element that can control current without moving parts, heated filaments, or vacuum gaps.

The amount of precipitation falling in one day, or other specified period, that is likely to be equalled or exceeded in any given place only once in a century. That is, a precipitation amount that has a return period of 100 years.

A sudden, significant increase in station pressure.

Same as pitot tube.

Instrument used to measure the amount of water evaporated from the soil surface during a given time interval.

Psychrometer to which a small chain or rotary handle is attached so that the observer can rotate the instrument rapidly to properly ventilate the thermometer bulbs.

See radiation shield.

Frozen or partly frozen rain.

Meteorological information issued by a watch office concerning the occurrence or forecast of weather phenomena which may affect the safety of aircraft operations.

Tables prepared from the psychrometric formula and used to obtain vapor pressure, relative humidity, and dew point from values of wet-bulb and dry-bulb temperatures.

A large plastic constant-level balloon for duration flying at very high altitudes.

Operation mode of a communication circuit in which one end can only transmit and the other end can only receive.

Same as evaporative power.

In a radiosonde observation, a level (other than a standard level) for which values of pressure, temperature, and humidity are reported because temperature and/or humidity data at that level is sufficiently important or unusual to warrant the attention of ...

Snow gauge composed of a metal cylinder, closed at one end, used to obtain a sample of snow from which the water is measured after melting.

An aneroid barometer with a scale graduated in altitude instead of pressure units.

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