Now that it’s turned cold, I’ve been getting electric shocks again. What causes them?
Static electricity is caused by a friction-induced charge separation which results from actions such as rubbing our feet on carpeting. Because water vapor attracts the free electric charges that the rubbing sets in motion, charges build up more easily when the air is very dry. In the warm season, air is relatively moist and water vapor is plentiful, lowering the accumulation of static electricity. Cold air contains little moisture, and humidity levels in our homes plunge when that air is heated, resulting in a sudden flow of current, or shock when you touch a conductor. Outdoor air at zero degrees with a relative humidity of 60 percent when heated in our homes to 72 degrees acquires a desert-like relative humidity of just 4 percent.