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What is the UV Index and how does it work?

Doppler 10 Futurecaster Lesson | It’s that time of year where you will hear the Doppler 10 weather team talk about the UV Index. It’s a standard measurement of the strength of sunburn-producing ultraviolet radiation at a particular place and time. ... The intensity of UV radiation, and thus the UV Index, depends on several factors: One being the Season. Because of seasonal sun angles -- The UV Index is highest in spring and summer. It goes down in the fall and is the lowest in the winter. Take a look at this chart --- the higher the number on the UV index, the stronger the sun’s rays are going to be and the quicker your skin can burn. When the Index is at a 1 or 2, it can take about an hour for your skin to burn – but when it jumps up to 8 or above – it could take as little as 15 minutes to get sunburn. The basic UV Index forecast is given for solar noon — the sun's highest point in the sky and the time of the highest fluctuation in UV radiation (under clear sky conditions). The SPF on your sunscreen stands for the Sun protection factor. An SPF of 15 blocks 93% of the sun’s UV rays – and SPF of 50 blocks 98% of those rays.