Is the ultraviolet ray strong on cloudy days or sunny days?
Ultraviolet rays are stronger in sunny days, generally divided into five grades, and the specific analysis is as follows:
The index value is 0 to 2, usually cloudy or rainy, when the ultraviolet intensity is the weakest, and the forecast level is 1 level;
The index value is 3 to 4, generally cloudy. At this time, the ultraviolet intensity is weak, and the forecast level is level 2;
The index value is 5 to 6, which is generally cloudy. At this time, the ultraviolet intensity is strong, and the forecast level is level 3;
The index value is 7 to 9, and it is generally cloudless on sunny days. At this time, the ultraviolet intensity is very strong, and the forecast level is 4;
The index value reaches or exceeds 10, and it is mostly sunny in summer, with particularly strong ultraviolet intensity, and the forecast level is five.