Will cloudy ultraviolet rays be weak? Will cloudy ultraviolet rays be weak?

1. The ultraviolet rays on cloudy days are not as strong as those on sunny days. The ultraviolet intensity is divided into five 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, usually showing particularly sunny weather.

2. Ultraviolet light refers to the light with the wavelength of 100 to 400 nanometers (nm) in sunlight, which can be divided into UVA (ultraviolet A, wavelength of 320-400 nanometers, long wave), UVB (wavelength of 280-320 nanometers, medium wave) and UVC (wavelength of 100-280 nanometers). Ultraviolet light is generated by the excitation of electrons in the outer layer of atoms. The main ultraviolet light source in nature is the sun. When sunlight passes through the atmosphere, ultraviolet rays with wavelength less than 290nm are absorbed by ozone in the atmosphere.