A scale of yellows, greens, and blues for recording the color of sea water, as seen against the white background of a Secchi disk.

A device which converts energy from one form into another, i.e. an ac generator transducer which converts the mechanical motion of anemometer cups into an electrical signal.

Generally, the relative states of inflow, outflow, and storage of moisture over a given area of earth's surface.

A unit of luminance or brightness equal to 1/d candles per foot'.

A mercury barometer arranged so that the position of the upper or lower meniscus may be measured photographically. In one design the image of the meniscus is formed on a rotating drum covered with sensitized paper so that a continuous record of pressure a ...

Same as pitot tube.

A seasonal wind of persistent direction, characterized by a pronounced change in direction between seasons.

A unit of illuminance or illumination equal to one lumen per foot'. This is the illuminance provided by a light source of one candle at a distance of one foot.

Radiation with wavelengths greater than 4 microns. (In meteorology, same as infrared radiation.)

modulated radiosonde-A radiosonde which transmits the indications of the meteorological sensing elements in the form of pulses spaced in time. The meteorological data are evaluated from the intervals between the pulses. Also called timeinterval radiosonde ...

A recording siphon barometer.

Moisture contained in the soil above the water table, including water vapor which is present in the soil pores. In some cases this term refers strictly to the humidity contained in the root zone of plants.

The line-of-sight distance between two objects.

A local variation in the wind direction or speed. This condition can present danger to aircraft, especially at landing, when a sudden shift from headwind to tailwind can cause a rapid loss of airspeed and lift.

Frozen or partly frozen rain.

Snow shower, particularly of a very light and brief nature.

Same as rain gauge.

Atmospheric layer throughout which there is no change of temperature with height, i.e. a zero lapse rate.

Precipitation of very small, white opaque particles of ice, fairly flat or elongated, with diameters less than 1 mm. The solid equivalent of drizzle.

Tables prepared from the psychrometric formula and used to obtain vapor pressure, relative humidity, and dew point from values of wet-bulb and dry-bulb temperatures.