Name applied to a class of instruments which measure the liquid content of the atmosphere.

Negative Vorticity Advection.

A small anemometer with flat vanes which indicates the number of linear feet or meters of air which have passed the instrument during its exposure.

A type of climatic diagram whose coordinates are some form of temperature vs. a form of humidity or precipitation.

An instrument that automatically records pressure and temperature.

An instrument for measuring radiant energy. It consists of an ether differential thermometer with blackened bulbs. One of the bulbs is exposed to the unknown radiation and the other to a black body source whose temperature can be varied. Equality of radia ...

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

Operation mode of a communication circuit in which each end can simultaneously transmit and receive.

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

Similar to the spectroheliograph, but used for visual instead of photographic purposes.

Same as ceiling light.

Any and all forms of water particles, liquid or solid, that fall from the atmosphere and reach the ground.

An instrument for taking photographs of an image of the sun in monochromatic light.

One of the radiation laws which states that the wavelength of maximum radiation intensity for a black body is inversely proportional to the absolute temperature of the radiating black body.

See hydrologic accounting.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

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

A radiosonde which is dropped by parachute from an aircraft for the purpose of obtaining soundings of the atmosphere below.

An instrument used for measuring the specific gravity of a liquid.

The direction, with respect to true north, from which the wind is blowing. Distinguish from magnetic wind direction. In all standard upper-air and surface weather observations, it is true wind direction that is reported.