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

Apparatus from which the nature and time of precipitation may be determined.

A clay atmometer consisting of a hollow ceramic sphere through which evaporation occurs. Evaporation is measured by the loss of water from the reservoir which feeds the sphere.

A hydrometeor consisting of a visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface.

A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

Very generally, any moving- stream of air. It has no particular technical connotation.

An instrument for the measurement of the rate of ice accretion on an unheated body.

Same as windsock.

A momentary decrease in the speed of the wind.

An instrument used to measure the water vapor content of the air.

Anemometer which generates an electrical contact output with a frequency proportional to wind speed.

An instrument for photographing the corona and prominences of the sun at times other than at solar eclipse.

Formation of a single water drop by the union of two or more colliding drops.

The stage on a fixed river gauge at which it is necessary to begin issuing warnings or river forecasts if adequate precautionary measures are to be taken before flood stage is reached.

A balloon used to carry a radiosonde aloft, considerably larger than pilot balloons or ceiling balloons.

An instrument used to measure changes in the level of the water in an evaporation pan. The gauge is normally placed in a Stillwell and adjusted so that the point of the hook just breaks the water surface. The change in water level is read on the attached ...

A general name for instruments which detect the presence of (but do not necessarily measure) small electrical charges by electrostatic means. Compare to electrometer.

Reduction of visibility by strong winds blowing across dry ground with little or no vegetation. Visibilities of 1/8 mile or less over a widespread area are criteria for a Blowing Dust Advisory.

A decrease in the central pressure of a pressure system. Usually applied to a low rather than to a high.

The downward flux of atmospheric radiation passing through a given level surface, usually taken as the earth's surface. This result of infrared (long-wave) absorption and reemission by the atmosphere is the principal factor in the greenhouse effect.