As always, thanks for submitting your Stump the Scientist questions! We appreciate everybody playing along with us! We’ve finally got some cold weather in Upstate New York so today’s question that came in from Facebook is especially fitting…
Question from Facebook fan Jason Burdorff:
Why is there more static electricity when there is cold weather? (or at least, why is it more noticeable?)
Response from Chief Scientist Jim Bray:
Static electricity refers to the separation of positive electrical charge (from the protons in atomic nuclei) from the negative electrical charges (from the electrons which surround all atoms). Normally, they exist next to each other in atoms such that everything is electrically neutral. However, some actions like friction (e.g., walking across a carpet, where shoes are sliding on the carpet) can separate these charges. Then, the extra charge on the shoes and person wearing them can discharge onto an uncharged object (like a doorknob), and we feel the small shock of “static electricity”.
This is more noticeable in cold weather because, in cold weather, the humidity is reduced in the air. Cold air contains less water than warm air, and we all have experienced the drier air indoors in the winter. It turns out that water molecules in the air speed up the discharge gradually of those things which have been electrically charged by static electricity. All things which are charged statically will eventually discharge, because that is their normal (lowest energy) state. However, in drier air, things retain their static charge longer, and we are more likely to have the time to notice the small shocks from the occasion discharges before the object discharge naturally.