A temperature telemeter.

A flower-like diagram indicating the relative frequencies of different wind directions for a given station and period of time.

Pyrheliometer based on the comparison of the heating of two identical metal strips, one exposed to radiation, the other to a joule effect.

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

Name given to the unit of pressure in the International System of Units (SI). Equal to 1 newton/meter2 or 0.01 millibar.

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

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

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.

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

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 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.

Ragged low clouds, usually stratus fractus. Most often applied when such clouds are moving rapidly beneath a layer of nimbostratus.

A unit of energy defined as the heat required to raise the temperature of one pound of water one degree Fahrenheit. It is equal to 252.1 calories or to 1055 joules.

A fabric cone attached to a metal ring and used to indicate wind direction. often at airfields.

An instrument for measuring temperature by utilizing the variation of the physical properties of substances according to their thermal states. Thermometers may be classified into types according to their construction; deformation thermometer, electrical t ...

See calorie.

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

An instrument used for measuring geometric angles. See radio direction-finder.

A motorlike device containing a rotor and a stator and capable of converting an angular position into an electrical signal, or an electrical signal into an angular position. When several synchros are correctly connected, all of the rotors will align thems ...

That horizontal wind velocity at which the Coriolis acceleration exactly balances the horizontal pressure force. It is directed along contour lines or isobars.