Question

How does "a circle bitten out by the teeth of winter" show personification?

Answer 1

Personification is when we give characteristics of people to inanimate things. In this case, Winter is inanimate (I mean it's not a person not a person). So when we say that Winter is "biting" something out, we see that as personification because Winter (a season) can't really literally bite things like we would bite a sandwich. 

Answer 2

It shows personification because it is implying that winter has teeth, and winter is biting, this is giving winter human-like characteristics, so therefore it is personification.

I hope I helped :)