When I was in beginning of spring, why did feathers fly out of the hole?

Beginning of spring is a solar term of the Spring Festival. When the ice freezes, it freezes layer by layer, but when it melts, it melts into vertical strips because of the upward geothermal airflow. It is easy for people to sink when they walk, so there is a saying that "ice turns stubble"

I heard from my grandmother that I have never experimented with this statement. Grandma said that when she was a child, she played this game, putting a thin bamboo tube into the soil and throwing a handful of dried chicken feathers. If chicken feathers fall and freeze on the soil of bamboo tubes before beginning of spring; After beginning of spring, he couldn't throw it in, as if someone was blowing at the other end.