One of several constant-pressure levels in the atmosphere for which a complete evaluation of data derived from upper air observations is required.

In folklore, a name for rain.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

Transmitted energy which is modulated in order to carry information. Usually, it is in the form of a radio- frequency sine wave, modulated either in amplitude or in frequency.

Part of a computer word that has meaning in itself, often, a byte.

A cup anemometer with its shaft mechanically coupled to a magneto.

The correction applied to an instrument to account for the effect of temperature upon its response characteristics.

check chamber-A chamber use to check the sensing elements of radiosonde equipment.

Programmable Read-Only Memory. Read-only memory which can be programmed by the user using a special hardware programmer.

An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.

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 ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

An anemometer which derives wind speed from measurements of dynamic wind pressures. Wind blowing into a tube develops a pressure greater than the static pressure, while wind blowing across a tube develops a pressure less than the static. This pressure dif ...

A liquid-in-glass or liquid-in-metal thermometer using mercury as the liquid.

A feeble oscillatory disturbance of the earth's crust, detectable only by very sensitive seismographs. Certain types of microseisms seem to be closely correlated with pressure disturbances. See microbarm.

An elongated area of relatively low atmospheric pressure. Usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow. The opposite of a ridge.

A hypothetical, ideal body which absorbs completely all incident radiation. independent of wavelength and direction. No actual substance behaves as a true black body, although platinum black and other soots rather closely approximate this ideal. However, ...

A recording anemoclinometer.

A method of winds aloft observation essentially the same as a pilot balloon observation except the height data is derived from the radiosonde observation rather than from assumed ascension rates.

The writing component of a recording instrument.