Pertaining to the action or effect of the wind. Derived from the name of the Greek god of the winds, Aeolus.

A self-recording thermometer.

A device for obtaining a continuous record of stage at a point on a stream. The most common recorders consist of a float-actuated pen which traces a record on a clock driven chart.

The average temperature of the air as indicated by a properly exposed thermometer for a given time period, usually a day, a month, or a year.

An instrument, dropped from high attitude and carried by a stable parachute. used to measure the vertical component of turbulence aloft.

The lowest value of a measured quality at which a sensor responds. Compare to tracking.

A wave disturbance in airflow due to some barrier in the flow. i.e. a hill or mountain.

In aviation terminology, route or terminal weather conditions of sufficiently low visibility to require the operation of aircraft under instrument flight rules.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

Same as precipitation- effectiveness index.

A device used to switch electrical current at a selectable setpoint temperature.

In meteorology, a deflecting force acting on a body in motion and resulting from the earth's rotation. It deflects air currents to the right in the northern hemisphere and to the left in the southern hemisphere, thus having an effect on wind direction.

Graduated fixed stake used in regions of abundant snowfall to facilitate the measurement of snow depth.

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.

A nephoscope in which the motion of the cloud is observed by its reflection in a mirror.

An aneroid barometer arranged so that the deflection of the aneroid capsule actuates a pen which graphs a record on a rotating drum. Sometimes called aneroidograph.

An instrument for measuring radiant energy. See actinometer, Dines radiometer, photometer, Tulipian radiometer.

in United States weather observing practice, the highest "instantaneous" wind speed recorded at a station during a specified period, usually the 24-hour observation day. Therefore, a peak gust need not be a true gust of wind.

Thermometer in which the difference in the rates of expansion with temperature of a liquid and its receptacle is used as a measure of the temperature. The liquid used may be ethyl alcohol, toluene, petroleum, or mercury.

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.