in Thoreau’s Journal:

Start for Amherst, N. H. A very cold day. Thermometer at 8a.m.— 8° (and I hear of others very much lower at an earlier hour), -2° at 11.45.

I find the first snow enough to whiten the ground beyond Littleton, and it deepens all the way to Amherst. The steam of the engine hugs the earth very close. Is it because it [is] a very clear, cold day?