The boundary between the troposphere and stratosphere, usually characterized by an abrupt change in lapse rate. Its height varies from 10 to 20 km. Regions above the tropopause have greater atmospheric stability than regions below.

A cone-tipped metal rod designed to be driven downward into deposited snow or firn. The measured amount of force required to drive the rod a given distance is an indication of the physical properties of the snow or firn.

A unit of energy equal to 1.356joules.

See aneroid capsule.

Same as wave pole.

meter-An instrument for measuring the transmissivity of the atmosphere; a type of transmissometer. It consists of a constant- intensity collimated light source located at a suitable distance from a photoelectric cell. Variation in the turbidity of the atm ...

See hook gauge.

A graduated scale placed in a position so that the stage of a stream may be read directly from it. Staff gauges may be placed on bridge piers or pilings, etc., or placed on specially constructed supports.

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.

Temperature of equilibrium between the liquid and vapor phases of a substance at a given pressure.

A general term for instruments designed to measure the amount of cloudiness.

The change in the measured transducer output caused by changes in ambient temperature. Usually expressed a percentage of full scale.

A type of pressure-plate anemometer in which the plate, restrained by a stiff spring, is held perpendicular to the wind. The wind-activated motion of the plate is measured electrically. The natural frequency of this system can be made high enough so that ...

Complementary Metal-Oxide Semiconductor. A method of making silicon chips that results in low power consumption by the circuits.

An instrument for measuring the extinction coefficient in water.

An instrument for recording global solar radiation.

The level at which ice crystals and snowflakes melt as they descend through the atmosphere.

Same as dew-point hygrometer.

Wind with a speed between 34 and 40 knots (39 and 46 mph); Beaufort scale number 8.

An up slope wind due to local surface heating. Opposite of katabatic wind.