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).

A rain gauge which automatically records the amount of precipitation collected, as a function of time.

A photometric unit of illuminance or illumination equal to one lumen per square centimeter.

Same as photometer.

A recording magnetometer.

A component of a radiosonde consisting of a series of alternate electrically conducting and insulating strips. As these are scanned by a contact the radiosonde transmits temperature and humidity signals alternately. The contact may be a baroswitch as in t ...

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 ...

The difference between the solar radiation directed downward and upward; net flux of solar radiation.

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.

A sudden brief increase in the speed of the wind, followed by a lull or slackening. Compare to peak gust.

The difference between downward and upward (total) radiation; net flux of all radiation.

A pyrheliometer of the thermoelectric type. Radiation is allowed to fall on two concentric silver rings, the outer covered with magnesium oxide and the inner covered with lamp black. A system of thermocouples (thermopile) is used to measure the temperatur ...

The record made by a hygrograph.

Water condensed onto objects at or near the ground, due to the fact that their temperatures have fallen below the dew point temperature of the surrounding air, but not below freezing.

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.

Operation mode of a communication circuit in which each end can simultaneously transmit and receive.

Same as river gauge.

Based upon damage patterns, classifies twisters into six categories of wind speed (F0 thru F5), ranging from 40 to 318 mph estimated wind speed.

An instrument which automatically determines the size distribution of raindrops.

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