紫し外がい線せん指し数すう

noun

ultraviolet index; UV index

A measure of the strength of ultraviolet radiation from the sun, commonly used in weather forecasts and health advisories.

• 今日きょうの紫し外がい線せん指し数すうは非ひ常じょうに高たかいので、日ひ焼やけ止どめを塗ぬってください。

  Today's UV index is very high, so please apply sunscreen.