(HealthDayNews) -- So there you are on vacation, basking on the beach and baking in that oh-so-warm sun, ignoring all those familiar warnings about sunburn.
The Southern Medical Journal offers a surprisingly simple rule for knowing when you've had enough sun: Stand up and look at your shadow.
The danger of a sunburn is directly related to ultraviolet radiation (UVR) intensity, which in turn is related to the angle of the sun -- its altitude above the horizon.
If your shadow is shorter than you are tall, the UVR from the sun is intense, and you are more likely to get a sunburn, the journal says. If your shadow is longer than you are tall, the UVR is not so intense, and you won't burn so easily.