A special form of the aspiration psychrometer. developed by Assmann, in which the thermometric elements are well shielded from radiation. Psychrometric measurements may be taken with the instrument in the presence of direct solar radiation.

An instrument for rapidly obtaining samples of airborne dust; a type of dust counter. Particles pass through a cylindrical chamber, are drawn at high velocity through a narrow slit, and then impinge upon a microscope cover glass located a short distance f ...

An instrument which determines the altitude of an object with respect to a fixed level. There are two general types of altimeters: (a) the pressure altimeter, which gives an approximate measure of altitude from a pressure measurement and an assumed standa ...

See captive balloon, ceiling balloon, constant-level balloon, free balloon, hurricane beacon, kytoon, Moby Dick balloon, pilot balloon, radiosonde balloon, rockoon, skyhook balloon, transosonde.

See river basin.

A method of streamflow routing which assumes that storage is a linear function of the weighted flow in the reach and is adaptable to a simple mathematical solution.

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

The record of a barograph.

Same as atmospheric pressure.

The portion of the strearnflow during any month or year derived from precipitation in previous months or years.

A computed characteristic of a particular river basin, expressed as the time difference between the time-center of mass of rainfall and the time-center of mass of resulting runoff.

A type of rain gauge shield consisting of freely hanging, evenly spaced slats arranged circularly around the gauge. The advantage of this shield is that the slats do not easily accumulate snow, permitting its use on unattended gauges. See rain gauge shiel ...

A unit of luminous intensity of a light source.

A cover which fits over a large inflated balloon to facilitate handling in high or gusty winds.

The stage, on a fixed river gauge, corresponding to the top of the lowest banks within the reach for which the gauge is used as an index. Compare to flood stage.

A rain gauge which indicates but does not record the amount of precipitation captured.

A thermometer using transducing elements which deform with temperature. Examples are the bimetallic thermometer and the Bourdon tube type of thennometer.

A constant which describes the performance of a wind vane in response to a step change in wind direction. It is calculated from the relative amount of overshoot on two successive swings (half cycles) of a decaying oscillation. This specification is dimens ...

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

An instrument used to determine atmospheric pressure or elevation by observing the boiling point of water or both liquids. The sensitivity of the hypsometer increases with decreasing pressure, making it more useful for high altitude work.