Eric Forshage asked:
As we head in to spring, my wife and I have had a debate concerning the efficacy of tanning while lying down, as compared to walking about. †
My wife contends that lying stationary while tanning if more effective than walking about without one's shirt on. †I have contended that the same number of photons would strike the subject regardless of movement.
Could you please settle this debate for us. †
An avid Yank listener.
Dave - I think it depends where youíre living. If youíre living on the equator, especially at midday, the Sun's going to be right above you at which point the only way youíll get the maximum amount of sun per square centimetre on your skin is to be at right angles to the Sun. If youíre somewhere near the equator and lie flat thatís probably going to be your best bet. If youíre living somewhere a long way North, like Sweden or Finland, then the Sun is very low on the horizon and the best way to get yourself at right angles to the Sun is to stand upright, so I think often in Russia and Sweden you get people going out sunbathing standing up, next to a wall. I think the only advantage of not moving around is possibly that you fall half asleep and time passes more quickly!
The distribution of the tan would be different in the two cases.
It's a question of momentum, the momentum have a vector and standing up, walking, the photons will find a lesser target to hit, depending on where the sun stands in relation to your 'spatzeiren'. I suspect your wife is right, and even if she's not you better agree :)
It's better to stay out on intense sunlight. It doesn't do anything good for your skin. Geezer, Mon, 9th May 2011
Eric Forshage asked the Naked Scientists: