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

See foehn.

Value of soil moisture, expressed as a percentage of the mass of dry soil, below which a plant living in the soil dies by wilting.

Snow gauge composed of a metal cylinder, closed at one end, used to obtain a sample of snow from which the water is measured after melting.

A photometer that measures the received intensity of a distance tight source.

An instrument which indicates the presence of dust particles in the atmosphere. Also spelled coniscope.

The source of illumination for an antenna reflector. Also called antenna feed.

Generally, an instrument designed to measure or estimate the blueness of the sky. See Linke-scale.

Root Mean Square. This notation is used frequently with error analysis. In that context, it is the square root of the arithmetic mean of the squares of the deviations of the individual calibration points from the theoretical or ideal response.

A system of physical units based upon the use of the meter, the metric ton (106 grams), and the second as elementary quantities of length, mass, and time, respectively.

An elongated area of relatively low atmospheric pressure. Usually associated with and most clearly identified as an area of maximum cyclonic curvature of the wind flow. The opposite of a ridge.

check chamber-A chamber use to check the sensing elements of radiosonde equipment.

The minimum temperature shown by a minimum thermometer exposed in an open situation with its bulb at the level of the tops of the grass blades of short turf.

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

The maximum distance along the runway at which the runway lights are visible to a pilot at touchdown. Runway visual range may be determined by an observer located at the end of the runway, facing in the direction of landing, or by means of a transmissomet ...

Programs or instructions which are stored in readonly memory.

Amount of water, expressed as a depth or as a mass, which would be obtained if all the water vapor in a specified column of the atmosphere were condensed and precipitated.

A reversing thermometer which is encased in a strong glass outer shell that protects it against hydrostatic pressure. Compare to unprotected thermometer.

The value of atmospheric pressure to which the scale of a pressure altimeter is set so as to indicate airport elevation. The altimeter setting is included as part of an aviation weather observation.

Capacity of a soil or other surface to be penetrated by water sinking into the ground under the force of gravity. It thus expresses the rate of percolation.