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Sunburn effect (as measured by the UV index) is the product of the sunlight power spectrum (radiation intensity) and the erythemal action spectrum (skin sensitivity) across the range of UV wavelengths. [9] [10] The UV index is a number linearly related to the intensity of sunburn-producing UV radiation at a given point on the Earth's surface.
Sunscreen, also known as sunblock, [a] sun lotion or sun cream, is a photoprotective topical product for the skin that helps protect against sunburn and prevent skin cancer. Sunscreens come as lotions , sprays, gels, foams (such as an expanded foam lotion or whipped lotion [ 4 ] ), sticks, powders and other topical products.
UPF (ultraviolet protection factor) represents the ratio of sunburn-causing UV without and with the protection of the fabric, similar to SPF (sun protection factor) ratings for sunscreen. While standard summer fabrics have UPF ~6, sun protective clothing typically has UPF ~30, which means that only 1 out of ~30 units of UV will pass through (~3%).
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The following table is listing suggestive relations of the lightfastness ratings on different measure scales and the relation relative to time in direct sunlight and normal conditions of display: away from a window, under indirect sunlight and properly framed behind a UV protective glass. [10]
Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun.
Sunburn is a form of radiation burn that affects living tissue, such as skin, that results from an overexposure to ultraviolet (UV) radiation, usually from the Sun.Common symptoms in humans and other animals include red or reddish skin that is hot to the touch or painful, general fatigue, and mild dizziness.
Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes. [2] Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the height of the Sun above the horizon, and atmospheric conditions. [3] Solar irradiance affects plant metabolism and animal behavior. [4]