Why does my hair stand on end when I take off my hat on a cold, dry day?

Question

Everything you see is made up of atoms. They contain even smaller particles, called protons and electrons. Protons have positive electrical charges and they never move. Electrons have a negative charge and they move around. Atoms usually have the same number of protons and electrons, so they cancel each other out and atom is neutral—it has no charge. When two things are rubbed together, sometimes the electrons move from one thing to the other. The atom that loses electrons becomes positively charged, and the atom that gets more electrons becomes negatively charged. Two things that have different charges pull toward each other; two things with the same charges push away from each other. When you take your hat off, electrons from your hat move on to your hair. Your individual hairs then have the same positive charge, so they move away from each other, and you look really funny.