Because less then 5% of the sun spectrum is ultraviolet radiation and 43% is visible light.

而太阳光谱中紫外光区占不到5%，可见光区则占43%。

youdao

Because less then 5% of the sun spectrum is ultraviolet radiation and 43% is visible light.

而太阳光谱中紫外光区占不到5%，可见光区则占43%。

youdao