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.

The standard deviation (positive square-root of the variation) of the errors associated with physical measurements of an unknown quantity, or statistical estimates of an unknown parameter or of a random variable.

An absolute temperature scale with the degree of the Fahrenheit scale and the zero point of the Kelvin scale. The freezing point of water equals 491.69

In general, any object that reflects incident energy. Usually it is a device designed for specific reflection characteristics.

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 ...

See calorie.

The range of operating conditions within which a device is designed to operate and for which operating influences are stated. See operating conditions, reference operating conditions.

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.

Difference between the temperatures of the dry-bulb and the wet-bulb thermometers of a psychrometer.

That part of snow melt that reaches stream channels as runoff.

The wind speed and direction at various levels in the atmosphere above the level reached by surface weather observations.

The direction, with respect to magnetic north, from which the wind is blowing. Distinguish from true wind direction.

The temperature at which a solid substance undergoes fusion, i.e. melts, changes from solid to liquid form. All substances have their characteristic melting points. For very pure substances the temperature range over which the process of fusion occurs is ...

A curve showing the variation of temperature with height in the free air. See lapse rate.

The depth of water that would result from the melting of snow or ice, assuming measurement on a horizontal surface and no infiltration or evaporation.

The lowest temperature that can be obtained on a wet-bulb thermometer in any given sample of air. Obtained by evaporation of water (or ice) from the muslin wick. Used in computing dew point and relative humidity.

A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. Compare to Pit ...

Any device or instrument for measuring salinity, especially one based on electrical conductivity methods.

The level at which ice crystals and snowflakes melt as they descend through the atmosphere.

A series of Nansen-bottle water samples and associated temperature observations resulting from one release of a messenger.