An instrument of the aspiration condenser type which measures the concentration and mobility of small ions.

General term for an instrument which records the vertical electric current in the atmosphere.

The lowest level at which the wind becomes geostrophic in the theory of the Ekman spiral. Also called gradient wind level.

Any one of numerous devices for the measurement of either speed alone or of both direction and speed (set and drift) in flowing water.

An anemometer utilizing the principle that the pitch of the aeolian tones generated by air moving past an obstacle is a function of the speed of the air. Largely a curiosity and has been put to no practical application in modem meteorology.

The cardinal points of the compass, i.e. north, south, east, west.

The process by which small particles suspended in a medium of a different refractive index diffuse a portion of the incident radiation in all directions. In scattering no energy transformation results, only a change in the spatial distribution of the radi ...

A hygrometer in which the sensitive element is a strand or strands of human hair, the length of which is a function of the relative humidity of the air.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the mass of dry air. For many purposes, the mixing ratio may be approximated by the specific humidity.

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

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

In general. the severe wind of an intense tropical cyclone (hurricane or typhoon). The term has no further technical connotation, but, unfortunately, is easily conftlsed with the strictly defined hurricane-force wind,

A rain gauge which automatically records the amount of precipitation collected, as a function of time.

The difference between the solar radiation directed downward and upward; net flux of solar radiation.

A recording anemoclinometer.

A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

For a given locality and month, an empirical expression devised for the purpose of classifying climates numerically on the basis of precipitation and evaporation.

Abbreviation for the pressure, temperature, and humidity data obtained by a radiosonde observation.

An element that can control current without moving parts, heated filaments, or vacuum gaps.

A c.g.s. (centimeter-gram-second) unit of mass. Originally defined as the mass of 1 cubic centimeter of water at 4