Albedo - Wikipedia article defines the term and offers examples of albedo effects.
Atmospheric Radiation Measurement Program - The ARM Facility has provided the world's atmospheric scientists with continuous observations of cloud and aerosol properties and their impacts on the Earth's energy balance for more than 20 years.
Glossary of Solar Radiation Resource Terms - University of Oregon Radiation Monitoring Laboratory started with the glossary from the National Renewable Energy Laboratory, edited and reformatted it, and added their own specialized terms.
NOAA Earth System Research Laboratory G-Rad - The Global Radiation Group's activities involve empirical and theoretical research of the Earth's surface radiation budget. The group specializes in the investigation of climatically significant variations in long-term radiation and meteorological measurements made primarily at a globally diverse network of surface sites.
Online Meteorology Guide: Light & Optics - University of Illinois
Solar Radiation Monitoring Laboratory - University of Oregon
Solar Resource Information - National Renewable Energy Laboratory
Stanford Solar Center - Targeted at 4th-12th grade students and science teachers, the site provides inquiry-based activities and a broad range of information relating to the sun. Solar art, folklore, music, literature, and archaeoastronomy complement the scientific information and offer intriguing multidisciplinary "hooks" into solar study.
Stratosphere: UV Index - Current UV Index forecast updated daily, archive of UV Index bulletins from June 1994, and other UV information from the Climate Prediction Center.
US Solar Resource Maps - These maps provide monthly average daily total solar resource information on grid cells. The insolation values represent the resource available to a flat plate collector, such as a photovoltaic panel, oriented due south at an angle from horizontal to equal to the latitude of the collector location. This is typical practice for PV system installation, although other orientations are also used.
USDA UV-B Monitoring and Research Program - The program was initiated in 1992, through a grant to Colorado State University, to provide information on the geographical distribution and temporal trends of UVB (ultraviolet -B) radiation in the United States. This information is critical to the assessment of the potential impacts of increasing ultraviolet radiation levels on agricultural crops and forests.
UV Index Forecasting Practices around the World - Craig S. Long, NOAA/NCEP
World Ozone and Ultraviolet Radiation Data Centre (WOUDC) is one of six world data centers which are part of the Global Atmosphere Watch program of the World Meteorological Organization.