Static Electricity — Winter's Tiny Lightning
That zap every time you touch a doorknob
In winter, pulling off a knit sweater makes your hair cling, and touching a car door goes "zap." Annoying, but the principle is interesting.
Electron Transfer
All materials have positive charges (protons) and negative charges (electrons), normally balanced. When two objects rub together, electrons transfer from one to the other.
Comb your hair with a plastic comb and the comb steals electrons from your hair. The comb becomes negatively charged, your hair positively charged. Like charges repel, so your hair spreads out everywhere.
Why Worse in Winter
Moisture conducts electricity. In summer's humid air, accumulated electrons gradually discharge through moisture in the air. In winter's dry air, this pathway doesn't exist. Electrons keep building up until you touch metal (doorknob) — instant discharge: "zap."
Relation to Lightning
Lightning is static electricity too. Inside clouds, ice particles collide and separate charges. The bottom of the cloud becomes negative, the top positive. When the potential difference exceeds a threshold, it discharges through the air. The only difference is scale: tens of thousands of volts vs thousands. The principle is exactly the same.
How It Works
Two objects rub → electrons transfer from one to the other
In dry conditions, electrons can't discharge and accumulate
Touching conductor (metal) causes instant discharge → spark and shock