What is UV index 0?

93 viewsOtherPlanetary Science

Lately there’s been about 30-40 minutes each afternoon where I can be outside in direct sunlight at UV 0, according to the weather app.

If high UV makes you more susceptible to burn, does 0 mean there’s no risk of burning at all? Would tanning in it be ineffective?

In: Planetary Science

Anonymous 0 Comments

The UV index is ( effective irradiance from 250-400nm, in watts/m^2 ) x 40.

If the UV index is truly, exactly zero, that means it’s nighttime and there’s no detectable UV coming in.

But keep in mind, if they report the UV index as a whole number, that means it could be as high as 0.499 and they’d round that down to zero…so an index of 0 *could* mean as much as 0.012499W/m^2 of radiation coming in. You could burn in that, but you’d have to have terrible genetics, use no sun protection and be exposed for hours.