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.

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 ...

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

A temperature telemeter.

The gravity flow of water within soil.

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 ...

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 radiosonde whose carrier wave is switched on and off in such a manner that the interval of time between the transmission of signals if a function of the magnitude of the meteorological elements being measured.

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

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

Nested Grid Model generated every 12 hours by NCEP.

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

An instrument for measuring differences of electric potential.

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 pressure-plate anemometer consisting of a plate which is free to swing about a horizontal axis in its own plane above its center of gravity. The angular deflection of the plate is a function of the wind speed. This instrument is not used for station mea ...

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

See calorie.