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

In meteorology, a deflecting force acting on a body in motion and resulting from the earth's rotation. It deflects air currents to the right in the northern hemisphere and to the left in the southern hemisphere, thus having an effect on wind direction.

A very sensitive electrostatic electrometer for measuring small potential differences.

For a given location, a measure of the long-range effectiveness of precipitation in promoting plant growth. Also called precipitation-evaporation index.

See captive balloon, ceiling balloon, constant-level balloon, free balloon, hurricane beacon, kytoon, Moby Dick balloon, pilot balloon, radiosonde balloon, rockoon, skyhook balloon, transosonde.

In a system of moist air, the dimensionless ratio of the mass of water vapor to the total mass of the system.

A unit of pressure which directly expresses the force exerted by the atmosphere. Equal to 1000 dynes/cm2 or 100 pascals.

Not a linear function of the relevant variables.

A unit of energy equal to 1.356joules.

A common type of liquid-inglass thermometer, used, in meteorology, in psychrometers and as a maximum thermometer.

An optical instrument which consists of a sighting telescope mounted so that it is free to rotate around horizontal and vertical axes, with graduated scales so that the angles of rotation may be measured. Used to observe the motion of a pilot balloon.

A graphical representation of a frequency distribution. The range of the variable is divided into class intervals for which the frequency of occurrence is represented by a rectangular column. The height of the column is proportional to the frequency of ob ...

Radiation with wavelengths less than 4 microns.

A line drawn through geographical points where a given seasonal biological event occurs on the same date.

Cathode Ray Tube. A display element, consisting of a vacuum tube and screen, used with computers.

A thermometer, invented by James Six in 1782, which simultaneously indicates the maximum and minimum temperatures attained during a given interval of time. A U-tube min/max thermometer

Same as precipitation-evaporation ratio.

An air-launched balloon designed to be released in the eye of a tropical cyclone, float within the eye at predetermined levels, and transmit radio signals for RDF positioning.

The meteorological visual range, which can be estimated from the average extinction coefficient using the Koschmieder equation.

An atmometer which uses a filter paper disc as the evaporating element. The amount of water evaporated through the paper is read at the graduated tube reservoir.