smoke ring

plural smoke rings

1. A vortex ring of smoke; typically one exhaled by a smoker.

   A smoke ring persists for a surprisingly long time, illustrating the slow rate at which viscosity dissipates the energy of a vortex.

   4 more examples

   Puff—puff—puff—went John’s pipe; and as the circling smoke-rings went up, the pictures therein framed became as distinct as if they had been drawn by the delicate pencil of Hammatt Billings.

   1854, John Ross Dix, chapter 2, in The Worth of the Worthless, Boston: Shakspeare Division of Sons of Temperance, page 46

   Then he lit his pipe, and leaning back in his chair he watched the blue smoke-rings as they chased each other up to the ceiling.

   1891, Arthur Conan Doyle, “The Five Orange Pips”, in The Adventures of Sherlock Holmes, published 1892

   He was blowing the most enormous smoke-rings, and wherever he told one to go, it went—up the chimney, or behind the clock on the mantelpiece, or under the table, or round and round the ceiling; but wherever it went it was not quick enough to escape Gandalf. Pop! he sent a smaller smoke-ring from his short clay-pipe straight through each one of Thorin’s.

   1937, J. R. R. Tolkien, chapter 1, in The Hobbit, New York: Ballantine, published 1982, page 13

   An extreme version of vorticity is a vortex. The vortex is a spinning, cyclonic mass of fluid, which can be observed in the rotation of water going down a drain, as well as in smoke rings, tornados and hurricanes.

   2013 March 28, Frank Fish, George Lauder, “Not Just Going with the Flow”, in American Scientist, volume 101, number 2, archived from the original on 01 May 2013, page 114