Aching Bones and Weather
Everyone has been told by a close friend that, "they know it is going to rain because their joints are aching". Most of us just smile at our friend, nod knowingly, and wonder if our friend also believes in little green men from Mars. But could there be a scientific explanation that supports and confirms this old wives' tale. I believe so!
When someone tells us that their joints ache due to impending rain they are referring to the bones in those joints. Unfortunately, there are almost no nerve endings in bone which can conduct the sensation of pain. This is due to the fact that bone is relatively solid and ultimately cuts off any nerve fibers and blood vessels, which initially fed it during our growing years. However, as many of us know when we break a bone we definitely feel that. So why the paradox?
Most bone is covered by a thin layer of tissue called the periosteum which means "around bone". The periosteum, unlike bone itself, is loaded with nerve endings which can conduct the sensation of pain. When a bone breaks it also tears the periosteum which surrounds the bone. This in turn fires off these nerve endings, which conduct the pain, which we experience when we break a bone. So by irritating or tearing the periosteum we know that we have broken a bone.
Predicting Weather from Aching Bones
But how does that explain how some people can "predict" when it is going to rain due to their achy joints? In two words, barometric pressure. When barometric pressure is rising we can expect bright skies and fair weather, when the barometric pressure decreases we can expect cloudy days with the chance of precipitation, rain or snow, increasing. And how does this affect the periosteum? When the barometric pressure rises that change exerts itself on the human frame and can actually cause a compression, although minute, of the bone. As a result the bone's diameter becomes smaller.
The opposite is also true when the barometric pressure falls. The decreasing pressure on the human frame allows the bones to expand, again minutely in diameter, but enough to exert pressure on, and stretch the periosteum. This in turns starts firing off those nerve endings, which relay pain, alerts to the brain and causes the aching in the joints. Unlike a fracture of the bone less nerve fibers fire off, hence the sensation of pain is diminished and we don't experience excruciating pain.
So the next time your friend tells you they think it might rain because of their aching joints you can now smile knowingly back at them and ask if they want to know why.