Of equal or constant pressure, with respect to either space or time.

Precipitation composed of balls or irregular lumps of ice with diameters between 5 and 50 mm.

An empirical curve relating stream discharge or stage at a point on a stream to discharge or stage at one or more upstream points and, possibly. to other parameters. Also called stage relation.

Water vapor content of the air. See absolute humidity, dew point, mixing ratio, relative humidity, specific humidity.

An instrument which measures evaporation by measuring the loss of water from a burette reservoir through a ceramic disc.

A wind vane used to obtain the horizontal and vertical components of the wind.

A thermoelectric thermometer used for measuring air temperature. The name is derived from the fact that the reference thermocouple is placed in an insulated bottle.

Anemometer which generates an electrical contact output with a frequency proportional to wind speed.

In thermodynamics, the integrating factor of the differential equation referred to as the first law of thermodynamics, In statistical mechanics, a measure of translational molecular kinetic energy (with three degrees of freedom). In general, the degree of ...

Thermometer for measuring the temperature in the soil at different depths.

The distance or length of flow of the air past a point during a given interval of time.

A common unit used in measurement of atmospheric pressure. Defined as that pressure exerted by a one-inch column of mercury at standard gravity and a temperature of 0'C.

A rainbow seen in the spray of the ocean. It is optically the same phenomenon as the ordinary rainbow.

A faintly-colored circular arc similar to a rainbow but formed on fog layers containing drops whose diameters are 100 microns or less. Also called mistbow, white rainbow.

Rate of wind movement in distance per unit time.

Name sometimes given to a transmissometer.

A class of rain gauge in which the level of the collected rain water is measured by the position of a float resting on the surface of the water.

A hydrometeor consisting of an aggregate of microscopic and more-or-less hygroscopic water droplets suspended in the atmosphere. It reduces visibility to a lesser extent than fog. The relative humidity of mist is often less than 95 percent.

The transducer of any hygrometer, i.e. that part of a hygrometer that quantitatively "senses" atmospheric water vapor.

Tables prepared from the psychrometric formula and used to obtain vapor pressure, relative humidity, and dew point from values of wet-bulb and dry-bulb temperatures.