noun
frost columns; ice needles
Needle-like ice crystals that form in soil when the ground freezes, pushing up small columns of earth. A winter phenomenon often noticed in gardens or bare ground.
今朝は冷え込んで、庭に霜柱が立っていた。
It was freezing this morning, and frost columns had formed in the garden.
霜柱を踏むと、サクサクと音がする。
When you step on frost columns, they make a crunchy sound.