Swallowed by Fog

We’ve been enjoying milder weather this past week, which has given us heavy fogs at night. We woke up this morning to a thick fog whiting out everything outside our yard. I thought I heard a train pass in the night, which gave me this verse — I believe this is called a tanka:

oh fog, how could you
swallow a whole freight train
in your opacity?
only the whistle escapes
to squeal on you