force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

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 ...

A diagram showing the intensity of the radiation field in all directions from a transmitting radio or radar antenna at a given distance from the antenna.

A current meter consisting of six conical cups, mounted around a vertical axis, which rotate and generate a signal with each rotation. Tail vanes and a heavy weight stabilize the instrument.

The distance or length of flow of the air past a point during a given interval of time.

The visibility along an identified runway, determined from a specified point on the runway with the observer facing in the same direction as a pilot using the runway. Compare to runway visible range.

The effect upon the measurement of rainfall caused by the presence of the rain gauge.

An instrument for measuring the pressure of gases and vapors. A mercury barometer is a type of manometer.

A sudden, significant increase in station pressure.

An instrument which automatically records the measurement of two or more meteorological elements.

Same as radiation pattern. Anticyclone-An area of high atmospheric pressure which has a closed circulation that is anticyclonic (clockwise in northern hemisphere and counterclockwise in southern hemisphere).

A relatively small-scale, upward moving current of air.

An absolute temperature scale with the ice point of pure water defined as 273.16 K. The size of the degree is the same as on the Celsius scale, and the zero point is absolute zero.

A mercury barometer of the fixed cistern type in which a moveable scale terminating in an ivory point is used to compensate for the variations in the height of the mercury in the cistern

Wind with a speed between 4 and 6 knots (4 and 7 mph), Beaufort scale number 2.

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 thermopile used in some types of radiation instruments. See solarimeter.

A graphical aid used in fire weather forecasting to calculate the degree of forest-fire danger (or burning index). Commonly in the form of a circular slide rule, the firedanger meter relates numerical indices of (a) the seasonal stage of foliage, (b) the ...

Any wind blowing down an incline. If warm, it is a foehn. If cold, it may be a fall wind or a gravity wind.

A unit of signaling speed representing the number of code elements sent per second; often, bits per second.