What is Solar Radiation?

The sun is essential for life on earth. Many vital processes on the earth’s surface, such as climate and life itself, are fuelled by radiation energy from the sun. About 99.98 per cent of the overall energy accountable for the global climate originate from the sun.

Electromagnetic radiation emitted by the sun ranges from gamma radiation of less than 0.1 Nanometer (nm) wavelength to long radio waves with a maximum wavelength at 500 Nanometer, i.e. in the yellow-green range of visible light.

The sun is a natural source of electromagnetic radiation and of optical radiation.

Optical radiation as part of solar radiation

Solar radiation comprises ultraviolet radiation (UV), visible light (VIS - "visible") and infrared radiation (IR). Solar radiation is usually called „Optical Radiation“, since it is deflected, scattered or reflected by optical systems such as lenses, mirrors or prisms.

The proportion of optical radiation from the sun reaching the ground varies largely. The intensity of the optical radiation primarily depends on

• the solar altitude (latitude, time of the day and the season of the year),
• the total ozone content of the absorbing atmospheric layer, and
• the cloud cover.

UV-exposure caused by the sun might be so intense as to produce negative effects on ecosystems. There is reason for concern that ozone depletion might give rise to a significant increase in UV-exposure, thus causing permanent harm to particular ecosystems.