The ratios, to the mean wind speed, of the average magnitudes of the component fluctuations of the wind along three mutually perpendicular axes.

Forecasting weather by the use of numerical models, run on high speed computers. Most of the NWP for the National Weather Service is done at the National Centers for Environmental Prediction (NCEP).

The difference between the input quantity applied to a measuring instrument and the output quantity indicated by the instrument. The inaccuracy of an instrument is equal to the sum of its instrument error and its uncertainty.

A modification of the dew cell used in radiosonde equipment.

February 2nd. In American folklore, a day that is popularly supposed to provide the key to the weather for the remainder of the winter. Specifically, if the ground-hog upon emerging from its hole casts a shadow, it will return underground, thereby forebod ...

Negative Vorticity Advection.

The temperature at which an object gives out as much radiation as it receives from its surroundings.

See sea-water thermometer, reversing thermometer.

A nephoscope in which the motion of the cloud is observed by its reflection in a mirror.

A device for measuring the height of tide. It may be simply a graduated staff in a sheltered location where visual observations can be made, or it may consist of an elaborate recording instrument (sometimes called a marigraph) making a continuous graphic ...

Instrument which measures and records the amount of evaporation over time.

Same as fogbow.

A calorimetric radiation instrument of historic interest used for the measurement of outgoing heat radiation from the earth during an interval of time. The time integration is performed by allowing the radiation to fall on an uninsulated vessel containing ...

A device that combines several separate communications signals into one and outputs them on a single line.

Hygrometer in which the dew (frost) point is determined by observing the temperature of an artificially cooled surface at the moment at which dew (frost) first appears on it.

The average temperature of the air as indicated by a properly exposed thermometer for a given time period, usually a day, a month, or a year.

The direction toward which the wind is blowing; with the wind.

An instrument which measures the transmissivity of the atmosphere between two points for the determination of visual range.

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

An instrument designed to measure the effect of sunlight on evaporation from plant foliage. It consists of a porous clay atmometer whose surface has been blackened so that it absorbs radiant energy.