Global Solar Radiation Measurement
Global solar radiation is the total amount of solar energy received by the Earth's surface, usually expressed as W m-2. About 99 percent of global solar radiation has wavelengths between 300 and 3000 nm. This includes ultraviolet (300-400 nm), visible (400-700 nm), and infrared (700-3000 nm) radiation. Global solar radiation is the sum of direct, diffuse, and reflected solar radiation. Direct solar radiation passes directly through the atmosphere to the Earth's surface, diffuse solar radiation is scattered in the atmosphere, and reflected solar radiation reaches a surface and is reflected to adjacent surfaces.
The visible portion of the solar radiation spectrum provides energy for photosynthesis, which is the primary gateway for inorganic carbon to become organic and support life on the Earth. Infrared light heats the ground and maintains an ideal environment for life. Global solar radiation drives the global water cycle and weather patterns. In fact, about half of the solar radiation absorbed by the Earth's surface is consumed by evapotranspiration on a global scale. Solar radiation is also used to generate electricity. Measuring global solar radiation can be accomplished with pyranometers and pyroheliometers.