Why does dry weather produce static electricity?

In the dry season, when you take off clothes made of synthetic fibers, you can often hear the sound of "snapping". If you are in the dark, you can still see sparks flashing on your clothes. Why is this?

In the dry and cold season, synthetic fiber clothes will rub against each other with the movement of the body. Friction will produce static electricity, and when static electricity accumulates to a certain amount, it will produce discharge phenomenon. This is the "pop" sound we hear and the sparks we see flashing on our clothes.

A little static electricity, one plane at a time? 1

1967, the US military invading Vietnam sent a batch of helicopters to the front to airlift the wounded. A helicopter full of wounded people flew over Saigon airport and was slowly landing when suddenly there was a loud landslide and the helicopter mysteriously exploded in the air!

Afterwards, American intelligence personnel rushed to the scene to investigate the tragedy and found that static electricity caused the disaster. In the process of taking off the sweater, the co-pilot of the plane generated strong static electricity, which led to fire and explosion. After this incident, pilots of the US Air Force were not allowed to wear sweaters, and their flight suits were redesigned.