The Great Gatsby, a sharp, wild brace

Could you please tell me the meaning of "sharp", "wild" and "brace" in the following excerpt from the last chapter of The Great Gatsby?

When we pulled out into the winter night and the real snow, our snow, began to stretch out beside us and twinkle against the windows, and the dim lights of small Wisconsin stations moved by, a sharp wild brace came suddenly into the air.

Thank you.