Smoke ring

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For Larry Niven's novel, see The Smoke Ring (novel).

Human blown smoke ring.

A smoke ring is a visible ring of fluid formed by expelling smoke through an opening. It is usually created by blowing smoke from the mouth, while smoking. It usually takes a lot of practice to learn how to do it.

Smoke ring from a smoke chamber

There are five different ways of making a smoke ring with the mouth. Although all require the formation of an 'O' with the mouth, they differ in the way the smoke is physically expelled. The first technique is to let smoke into the mouth, then gently flick the tongue to expel a short burst of smoke. The second is to let smoke into the mouth, then while pushing the jaw out, slowly open and close the jaw to push smoke out. The third is to form the 'O' with the lips, then gently say just the very beginning of 'Oh'. The fourth technique is to let smoke into the mouth, and then tap your cheek. The fifth technique differs from the previous three in that one does not need to fill up the mouth with smoke beforehand because the smoke is actually being expelled from the lungs, not the mouth. Most smokers blow rings using some combination of these five techniques.

In general, a smoke ring occurs when a mass of fluid (from the mouth, lungs, or another reservoir) is impulsively pushed through a roughly circular opening, forming a vortex ring just outside of the opening. The smoke ring travels roughly straight from the opening and maintains its shape until dispersed by turbulence or other interference. The smoke serves to make the flow pattern of the air visible, and does not significantly affect the fluid behavior.

The other method of creating a smoke ring involves releasing a mass of fluid with a different density than the surrounding fluid. This can be done in several ways:

Releasing air underwater forms rings of bubbles. Scuba divers often do this, and dolphins have also been observed performing this trick.^[1]

A vortex ring or smoke ring can be formed in the atmosphere by a rising (falling) mass of warm (cold) air, which is also called a thermal (microburst). One is occasionally at the core of a mushroom cloud, and they can be seen at fire eater presentations.

A lit cigarette can be used to create a smoke ring. To do this, hold a cigarette vertically and quickly raise it about 4 inches, then gently pull the cigarette down. This creates the vortex needed to create a smoke ring.

A trick often done in conjunction with mouth-blown smoke rings, is the French inhale.

A smoke ring is also the name for the pink ring that forms around the edges of meat prepared by Texas barbecue, caused by myoglobin in the meat reacting with carbon monoxide to form a heat stable pigment.^{[citation needed]}