In the dry winter, you may have had this experience, when you have a carpeted walkway came to the door of the room, hand in contact with the metal door of the moment
It is because the winter weather is too dry, clothes and body friction larger, prone to static electricity, resulting in static electricity will produce a weak current, which will hear the "pop" sound
It is the phenomenon of electrostatic discharge, human clothing in the friction so that the local electrical uneven, stripped of course, will discharge and see the spark heard the sound. Door handles and people with your body with dissimilar charge can easily become your discharge object. Friction of the friction of the amber with energy to attract hair, because the hair is not charged, the discharge is naturally not obvious.
