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. Its maximum lies at a wavelength of 500 nanometers, i.e. in the yellow-green range of visible light.

The sun is a natural source of optical radiation which is part of the electromagnetic spectrum.

Optical radiation as part of solar radiation

Ultraviolet radiation (UV), visible light (VIS) and infrared radiation (IR) are part of solar radiation and are combined as „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 season of the year),
• the total ozone content of the absorbing atmospheric layer, and
• the cloud cover.

Solar optical radiation - especially UV radiation, but also infrared radiation (heat radiation) - has positive and negative effects on humans and the environment. For this reason the solar UV radiation is permanently recorded and evaluated worldwide as an important environmental factor in addition to other meteorological parameters such as temperature and precipitation - not least due to the processes in the atmospheric ozone layer related to climate change.