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 description or explanation of the manner in which the height of the ceiling is determined, i.e. aircraft ceiling, balloon ceiling. estimated ceiling, indefinite ceiling, measured ceiling, precipitation ceiling.

A type of cloud height indicator which uses a searchlight to project vertically a narrow beam of light onto the cloud base. The height of the cloud is determined using a clinometer, located at a known distance from the ceiling light, to measure the angle ...

Same as ceiling light.

An automatic, recording cloud height indicator.

Interational thermometric scale on which the freezing point of water equals 0

The pressure unit of the meter-ton-second system of physical units. equal to 10 millibars or 101 dynes per cm2.

The older name for the Celsius temperature scale. Officially abandoned by international agreement in 1948, but still in common use.

A system of physical units based on the use of the centimeter, gram. and the second as elementary quantities of length. mass. and time.

The water volume within a specified portion of a stream channel.

Part of a computer word that has meaning in itself, often, a byte.

A clock-driven device for recording the time of occurrence of an event or the time interval between the occurrence of events.

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.

A thermometer consisting of a clock mechanism the speed of which is a function of temperature.

A mercury barometer in which the lower mercury surface is larger in area than the upper surface. The basic construction of a cistern barometer is as follows: A glass tube one meter in length, sealed at one end is filled with mercury, and then inverted. Th ...

See evaporation pan.

An atmometer consisting of a porous porcelain or ceramic container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.

Turbulence encountered by aircraft when flying through air space devoid of clouds. Thermals and wind shear are the main causes.

An instrument for measuring angles of inclination. Used in conjunction with a ceiling light to measure cloud height at night.

A hydrometeor consisting of a visible aggregate of minute water and/or ice particles in the atmosphere above the earth's surface. Cloud differs from fog only in that the latter is, by definition, in contact with the earth's surface.