Needle ice is formed when the ground is above freezing but the air is below freezing. Water in the soil rises to the surface and freezes, forming tiny needles of ice that often push the top layer of soil two or three centimetres into the air.
Here we see a 'bundle' of needle ice, about 3cm long, showing the fine hair-like structure formed as it is created. The individual needles are frozen together at the edges, but most will easily break apart into individual strands.