A pointed device which indicates the amount of resistance encountered when it is forced into a material such as snow or soil. See ram penetrometer.

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

Overflowing by water of the normal confines of a stream or other body of water, or accumulation of water by drainage over areas which are not normally submerged.

Apparatus using the combined simultaneous action of a bimetallic thermometer and a hair hygrometer to move a needle in front of a divided scale. fts construction permits dew point variations to be indicated approximately.

An automatic, recording cloud height indicator.

A small pointer extending downward from the top of the cistern of a Fortin barometer. The level of the mercury in the cistern is adjusted so that it just comes in contact with the end of the pointer, thus setting the zero of the barometric scale.

A direct-vision nephoscope which is constructed in the following manner: a comb consisting of a crosspiece containing equispaced vertical rods is attached to one end of a column eight to ten feet long and is supported on a mounting that is free to rotate ...

Automated Weather Observing Station. A self-contained weather station designed to make aviation weather observations without operator involvement.

A sunshine recorder of the type in which the time scale is supplied by the motion of the sun. It consists of two opaque metal semi-cylinders mounted with their curved surfaces facing each other. Each of the semi-cylinders has a short narrow slit in its fl ...

An instrument which measures the effective terrestrial radiation. See Angstrom pyrgeometer.

The cardinal points of the compass, i.e. north, south, east, west.

A thermodynamic change of state in a system in which there is no transfer of heat or mass across the boundaries of the system. In an adiabatic process, compression always results in warming, expansion in cooling. Compare to diabatic process.

Radiation with wavelengths greater than 4 microns. (In meteorology, same as infrared radiation.)

An instrument, for the recording of two or more meteorological parameters, in which the ventilation is provided by a suction fan.

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

The upward force produced by the gas in a balloon. It is equal to the free lift plus the weight of the balloon and the attached equipment.

A large plastic constant-level balloon for duration flying (in excess of 24 hours) at altitudes above 40,000 feet, used for the determination of wind fields and the measurement of upper atmospheric parameters.

A wind scale adapted by the U.S. Forest Service for use in the forested areas of the northern Rocky Mountains (NRM). It is an adaptation of the Beaufort wind scale. The difference between these two scales lies in the specification of the visual effects of ...

A type of disk hardness-gauge, especially useful in relatively soft snow. See disk hardness gauge.

The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the "column" of air lying directly above the point in question.