The envelope of air surrounding the earth and bound to it more or less permanently by virtue of the earth's gravitational attraction. The system whose chemical Properties. dynamic motions, and physical processes constitute the subject matter of meteorolog ...

An instrument that shows changes in humidity.

Fine dust or salt particles dispersed through a portion of the atmosphere; a type of lithometer. The particles are so small they cannot be felt or seen with the naked eye. Many haze formations are caused by the presence of an abundance of condensation nuc ...

A cup anemometer with its shaft mechanically coupled to a magneto.

The intensity (flux per unit solid angle) of visible radiation weighted to take into account the variable response of the human eye as a function of the wavelength of light. Usually expressed in candles.

Readily taking up and retaining moisture.

A strong wind characterized by a sudden onset, a duration on the order of minutes, and a rather sudden decrease in speed.

The record made by a hygrograph.

A standard unit of atmospheric pressure, defined as the pressure exerted by a 760 mm column of mercury at standard gravity (980.665 cm/sec2 ) at O

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

Not a linear function of the relevant variables.

An aneroid barometer with a scale graduated in altitude instead of pressure units.

Electromagnetic radiation lying within the wavelength interval to which the human eye is sensitive, the spectral interval from approximately 0.4 to 0.7 microns (4000 to 7000 angstroms). Bounded on the short-wavelength end by ultraviolet radiation and on t ...

A small balloon used to determine the height of the cloud base. The height can be computed from the ascent velocity of the balloon and the time required for its disappearance into the cloud.

A type of atmometer. It is a pan used in the measurement of the evaporation of water into the atmosphere. The NWS Class A pan is a cylindrical container 48 inches in diameter and 10 inches deep.

The depth below which the ground is saturated with water. No water table exists if the ground water is confined by an overlying impermeable stratum, as in the case of artesian ground water.

A diagram showing the intensity of the radiation field in all directions from a transmitting radio or radar antenna at a given distance from the antenna.

The difference between the air temperature and the dew-point. Also called dew-point deficit, dew-point depression.

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

Same as mirror nephoscope.