Defect in the action of an aneroid barometer resulting in a sluggish adjustment of the index toward the correct reading when the barometer is subjected to a large and rapid change in pressure.

A pressure-operated switching device used in a radiosonde. In operation, the expansion of an aneroid capsule causes an electrical contact to scan a radiosonde commutator composed of conductors separated by insulators.

Abbreviation for precipitation-evaporation ratio.

A unit measure of electrical conduction. The facility with which a substance conducts electricity, as represented by the current density per unit electrical-potential gradient in the direction of flow. Electrical conductivity is the reciprocal of electric ...

A recording hair hygrometer.

The standard deviation of a sufficiently large number of measurements of the same quantity by the same instrument or method. The non-correctable part of the inaccuracy of an instrument, it represents the limit of measurement precision. The uncertainty of ...

The line-of-sight distance between two objects.

The nautical mile is closely related to the geographical mile which is defined as the length of one minute of arc on the earth's equator. By international agreement, the nautical mile is now defined as 1852 meters.

In physics, any process in which the flux density (or power, amplitude, intensity, illuminance, etc.) of a "parallel beam" of energy decreases with increasing distance from the source. Attenuation is always due to the action of the transmitting medium its ...

A sounding balloon which, when operationally inflated, resembles an inverted teardrop.

Movernent of water through the soil surface into the soil, or the quantity of water entering the soil. Infiltration is equal to the total precipitation less the losses due to interception by vegetation. retention in depressions on the land surface, evapor ...

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

Extended Binary Coded Decimal Interchange Code. A standard code used to represent data using 8 bits per character.

An aviation weather forecast for a specific flight.

A thermometer based upon the principle that the velocity of a sound wave is a function of the temperature of the medium through which it passes. Sonic thermometers possess very short time-constants and eliminate radiation error.

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

A temperature scale on which the freezing point of water equals 32

The interval between the lower and upper measuring limits of an instrument, i.e. a thermometer with a range of -35 to 50

A graphical aid used in the reduction of data from a winds aloft observation.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.