<P> Sunlight is a portion of the electromagnetic radiation given off by the Sun , in particular infrared , visible , and ultraviolet light . On Earth , sunlight is filtered through Earth 's atmosphere , and is obvious as daylight when the Sun is above the horizon . When the direct solar radiation is not blocked by clouds , it is experienced as sunshine , a combination of bright light and radiant heat . When it is blocked by clouds or reflects off other objects , it is experienced as diffused light . The World Meteorological Organization uses the term `` sunshine duration '' to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per square meter . Other sources indicate an `` Average over the entire earth '' of `` 164 Watts per square meter over a 24 hour day '' . </P>
where does the sun 's visible light come from
direct solar radiation is not blocked by clouds