What weather has the strongest ultraviolet rays? Why?

1. Ultraviolet rays are strongest when the weather is particularly clear.

The ultraviolet intensity is divided into 5 levels: 1 level is the weakest, which usually indicates rain; Level 2 is weak and generally cloudy; Level 3 is medium, generally cloudy, and occasionally a little sun can be seen from the clouds; Level 4 is strong, generally sunny; Level 5 is the strongest, which usually means that the weather is particularly sunny.

2. Wan Li is clear in summer, 1 1- 15, which is closest to the sun and has no cloud cover. Ultraviolet rays are strongest where the sun shines directly.