Ultraviolet Rays
Ultraviolet
noun
The purple outside line is the color spectrum that's outside purple. Those are ultraviolet rays (the lines are the rays).
紫外線 is a technical term, but you'll come across it a lot in everyday 紫外線対策 (UV protection) contexts like weather reports, skincare, or health talk.
This is a jukugo word that uses the on'yomi readings of the kanji. You didn't learn the on'yomi reading of the 紫 kanji, so here's a mnemonic to help you remember:
Do you know what animal has the best protection from ultraviolet rays? Sheep (し), obviously. Their thick wool is the best UV protection. I mean, you've never seen sheep tanned and sunburned, right?
紫外線対策
ultraviolet protection measures
紫外線吸収剤
ultraviolet absorber
紫外線カット
ultraviolet blocking
紫外線照射
ultraviolet irradiation
紫外線を浴びる
to be exposed to ultraviolet rays
紫外線を吸収する
to absorb ultraviolet rays
紫外線をカットする
to block ultraviolet rays
紫外線を照射する
to irradiate with ultraviolet rays
紫外線を防ぐ
to protect against ultraviolet rays
紫外線が強い日は、外に出たくありません。
On days when the UV rays are strong, I don't want to go outside.
夏は紫外線対策が欠かせません。
In the summer, UV protection is essential.
紫外線は目にもダメージを与えるので、紫外線カットのサングラスを買いました。
Ultraviolet rays can also damage your eyes, so I bought UV-blocking sunglasses.