From Where I Lived, and What I Lived For by Henry David Thoreau:
This small lake was of most value as a neighbor in the intervals of a gentle rain-storm in August, when, both air and water being perfectly still, but the sky overcast, mid-afternoon had all the serenity of evening, and the wood thrush sang around, and was heard from shore to shore.
A gentle rain storm seems odd to me, isn't it to be at least at some degree of furious to be qualified as a storm? How can gentle be the adjective of a storm?