The air is obviously cold, because I can see my breath as I exhale in my early morning walk to the barn. Most mornings, I don’t see my breath. But four months of the year I have a pretty good chance, as I live in the mountains along the Eastern Continental Divide. Those first few breaths on a frosty morning can be invigorating. It is visual evidence that I am alive. In years past, people would hold a small mirror to someone’s nose and mouth to tell if they were still alive. The mirror would register even the faintest breath, fogging over. …