Glossary of Solar Radiation Resource Terms

Other relevant glossaries


The following links allow you to move to the words beginning with that letter.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Water Vapor - gaseous water (individual water molecules) in the atmosphere.


Watt - a unit of power defined as a joule per second.


Watt-hour - a unit of energy equal to 3600 joules.


Wavelength - the distance between adjacent peaks or troughs of a wave. Wavelengths of light are typically expressed in terms of Angstroms or nanometers (10-9 meters).


WBAN - the Weather Bureau/Army/Navy identifier of weather stations. This five-digit code is unique to each weather measurement station in the WBAN system.


Weather - the state of the atmosphere at a given time. This includes temperature, humidity, cloud cover, precipitation type, and presence of aerosols.


Wet-bulb Temperature - the temperature to which air will cool when water is evaporated into unsaturated air; measured by a wet-bulb thermometer, which has a wet cloth sleeve that covers its bulb. Wet-bulb temperature and dry-bulb temperature are used to compute relative humidity.


Wind - horizontal motion of air near the surface of the Earth.


Wind Rose - polar graphs that indicate the speed and relative duration of wind according to its direction. Wind roses are useful for determining the most prevalent direction of winds of desired strength. Wind roses are reported at NREL's Solar Radiation Research Laboratory.


WMO - the World Meteorological Organization.


WRR - the World Radiometric Reference, which provides the basis for all measurements by radiometers in the world. Every five years, many of the best absolute cavity radiometers undergo an intercomparison at PMOD/WRC (Davos, Switzerland). The most stable, accurate, and precise instruments provide the World Radiometric Reference for the coming years. Any credible radiometer measurement must be traceable to the WRR.


WSG - the World Standard Group (WSG) of absolute cavity radiometers is maintained by the World Meteorological Organization's (WMO) World Radiation Center (WRC) (Davos, Switzerland). The WSG is a group of seven well-characterized absolute cavity radiometers used to define the World Radiometric Reference (WRR). International intercomparisons of national standard pyrheliometers with the WSG are held every five years at the WRC to transfer the WRR to national centers. Having participated in such comparisons since 1980, NREL has three absolute cavity radiometers directly traceable to the WRR. The WRR has an uncertainty of less than +/- 0.3%. This means that the best possible measurements of direct normal solar irradiance have at least this uncertainty.


WYEC - the Weather Year for Energy Calculations, a "typical year" used by engineers and architects of ASHRAE.


The following links allow you to move to the words beginning with that letter.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z



Please send questions and comments to the webmaster

Disclaimer and copyright notice

Return to RREDC Home Page ( http://rredc.nrel.gov/ )