Reflection is just as effective as absorption. As long as the UV isn’t passing through the fabric into you, you are fine.
Well butter my biscuit, I might be wrong.
There are other of factors to take into account, but it makes sense that, the portion of light that does make it through a light fabric will keep on reflecting inside the garment until it is absorbed or escapes back out. Like a photography light box.
I don't have the highest degree of confidence in it but it makes sense to me that absorption matters more than reflection because a lot of the reflected UV will be going through the shirt and onto your skin
That's why materials like linen aren't as good for UV protection. They're light weaves and let a lot of light through, still
Its a bit misleading. Black clothes will absorb the heat from the sun and your body and then the clothes will cool via convection. So the wind blowing through the clothes takes the heat away. White will reflect the heat from the sun away and your body back towards you.
Im sure theres some debate and probably way more to it but i have always felt more comfortable in the heat than other people and i wear darker clothes the majority of the time. If that anecdote bares any weight.