Billowing or bellowing?

I came across “a train bellowing smoke” in a client’s presentation last week. This unintentionally poetic line sounded like something Henry David Thoreau would have penned — a train roaring along with smoke screaming out of it. “Bellowing” is a deep shout, but the correct word is “billowing,” which means “to rise or roll in waves.” It’s not a common mix-up to come across in a piece of writing, but it’s definitely an interesting one!