Every light source emits light with a colour temperature, measured in kelvins or the symbol K. The biggest source is the sun but the colour of its light varies depending on where it is in the sky, the location and atmospheric conditions. At midday on a clear day, its output is around 5500-5700K although it will be higher and cooler at the beach or in the mountains.
The colour temperature also rises and gets more blue if it clouds over, while at sunset when the sun is low
