UV Index VS time needed to get sunburnt (snow, average, days)

[EricS39]

Question rather is, does UV Index represent part of UV-A and UV-B intensity?

Otherwise how is it possible the UV Index is a linear scale,

Fairbanks Alaska is getting UV Index 4 under clear weather,
Solar noon in Fairbanks is not much higher than sun 45 degrees in the sky


UV-B irradiance at 45 degrees in the sky is only around 10% of maximum possible exposure

But the UV index is 40% of ITS max possible exposure

[Ariete]

Vai niin. (Ok then in English)

How many decimals of the pi can you... forget about it.

[P London]

One thing I don't get is how when forecasting UV and sunburn they don't take in akin pigmentation in consideration I mean a black guy isn't going to get suburnt as quick as a white woman

[EricS39]

I am working on a model to adjust for skin pigmentation

I think but may be wrong, UV index raw scale reflects damage to a person with reasonably light skin but not fairest of fair ...on a day with weather as predicted in the forecast, for the 2pm-ish hour of sun

Wave lengths of UV from shortest uV-b to largest uv-a are averaged together and weighted by 1) % present per sun angle and 2) relative harm to human body

Keeping in mind the shorter the wave length, the more harmful the unit of exposure but also the more direct the sun angle needed to bring it on and the more it is sensitive to ozone depletion

[EricS39]

Successfully modeled UV index pretty closely. A lot of misinformation out there

Some say UV-A hardly changes from sunrise to noon. That's only true for the very long range of UV-A wavelengths

However, clearly the fact that UV-B is not much present until sun is 40 degrees above horizon, except under snow terrain and mountains and ozone hole, and the fact that UV index at sunrise is near 0, most of UV-A does get more intense as day progresses but just not as sensitive to atmosphere penetration as UV-B

Enough that when you weight all wavelengths 290nm to 400nm, UV index is almost a linear function of the solar zenith angle

[chicagogeorge]

One of the worst sunburns I ever had was when I fell asleep on my deck during a cloudy day a few years ago. Had a couple of Bloody Mary's in the AM and I woke up 2 hours later and was beet red... and I have more of an olive complexion. Cloudy days can give you a false sense of security, and our sun angle max in the summer is only 71.5 degrees. Always use sunscreen!

[Bottletree]

Diet plays a big role in sunburn.

Read an article before that Americans are more more likely to get it because of the trans fat. The Greeks on the other hand have better diet which is why they are less affected.

Greece has one of the lowest skin cancer rates despite being at 37N and sunny summers.


Found it:

Skin cancer