A mercury barometer designed for use aboard ship. The instrument is of the fixed-cistern type (see Kew barometer). The mercury tube is constructed with a wide bore for its upper portion and with a capillary bore for its lower portion. This is done to incr ...

The height at which the maximum wind speed occurs, determined in a winds-aloft observation.

Anemometer which measures wind speed by measuring the degree of cooling of a metal film heated by an electric current. A type of cooling-power anemometer.

Integrated Flood Observing and Warning System. National Weather Service flood warning program.

An instrument for studying, or examining substances in, polarized light. See Savant polariscope.

A self-recording psychrometer.

Old snow that has become granular and compacted as a result of melting and refreezing.

A modification of the dew cell used in radiosonde equipment.

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

Of or pertaining to rain.

Same as aneroid barometer. Holostelic means wholly made of solids, while aneroid means devoid of liquid.

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.

A surface weather observation, made at periodic times, of sky cover, state of the sky, cloud height, atmospheric pressure reduced to sea level, temperature, dew point, wind speed and direction. amount of precipitation, hydrometeors and lithometeors. and s ...

A hydrometeor consisting of a visible aggregate of minute water droplets suspended in the atmosphere near the earth's surface. Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface.

Solar radiation of selected wavelengths.

Temperature to which absolutely dry air would have to be brought in order for it to have the same density as moist air, considered at the same pressure.

An instrument used for measuring the specific gravity of a liquid.

A wooden enclosure about sixteen feet square and eight feet high with a precipitation gauge at its center. The function of the fence is to minimize eddies around the gauge and thus insure a catch that is representative of the actual rainfall or snowfall.

Barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.

An inert gas. An element found in the atmosphere to the extent of only 0.000114 percent by volume. Its molecular weight is 83.7.