Sunlight

Sunlight is electromagnetic radiation in the visible and near visible region of the electromagnetic spectrum. The visible light we see is a small subset of the electromagnetic spectrum shown in Figure 1.1 in grey. The breakdown of frequencies is as follows:

ultraviolet C (UVC): 100–280 nm. Absorbed in the earth’s upper atmosphere;

ultraviolet B (UVB): 280–315 nm. Normally absorbed in the earth’s upper atmosphere by the ozone layer (but absorbed less if the ozone layer has been depleted);

ultraviolet A (UVA): 315–400 nm. (e.g. as used in tanning and therapy for psoriasis);

visible: 400–700 nm. The range commonly used by photovoltaic cells to produce electricity;

infrared: 700 nm–10⁶ nm (1mm).