# Making "Smoke" In Your Mouth

**URL:** <https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510>\
**Category:** Factual Questions\
**Created:** [May 15, 2014, 6:26am UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510 "2014-05-15T06:26:34Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\
**Post date:** [May 15, 2014, 6:26am UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/1 "2014-05-15T06:26:34Z")

</div>

Has anyone ever tried this: collect air in your mouth. Cover your mouth with a finger and compress the air (use your tongue and mouth muscles, not your lungs). Look at a dark background, stick your lower jaw and lip out so air blows upwards, and gently sigh. Do you see a cloud/fog/smoke? How does this work?

---

<div class="post-metadata">

**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\
**Post date:** [May 15, 2014, 12:14pm UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/2 "2014-05-15T12:14:59Z")

</div>

It sounds like how I “see my breath” in cold weather. And my upper lip and the bottom of my nose feel the warmth. It’s basically just water vapor.

---

<div class="post-metadata">

**Author:** ![CheshireKat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheshirekat/32/1207_2.png) [@CheshireKat](https://boards.straightdope.com/u/CheshireKat)\
**Post date:** [May 15, 2014, 1:48pm UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/3 "2014-05-15T13:48:44Z")

</div>

If you place a drop of detergent between your lower teeth and inner lip you can blow smoke bubbles. 😃

---

<div class="post-metadata">

**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\
**Post date:** [May 15, 2014, 1:59pm UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/4 "2014-05-15T13:59:04Z")

</div>

I haven’t noticed that type of smoke before but it did remind me of something I used to do as a kid. Take an empty gallon milk jug and compress as much air as you can. As in the OP, the tongue and mouth are doing the work here. When you release the pressure, _smoke_ can be seen rising from the jug. _wiggles fingers magician-style_  
I haven’t thought about that in decades.  
My other milk jug trick involves actual fire and only incidental smoke.

---

<div class="post-metadata">

**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\
**Post date:** [May 15, 2014, 2:00pm UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/5 "2014-05-15T14:00:00Z")

</div>

Works really well. I can blow out a huge amount of smoke. Hold on, I’m going to put this cigarette out and try again.

---

<div class="post-metadata">

**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\
**Post date:** [May 15, 2014, 2:15pm UTC](https://boards.straightdope.com/t/making-smoke-in-your-mouth/688510/6 "2014-05-15T14:15:30Z")

</div>

> [@panache45](#):
>
> It sounds like how I “see my breath” in cold weather. And my upper lip and the bottom of my nose feel the warmth. It’s basically just water vapor.

I thought so, but you aren’t doing anything to cool the air in your mouth. Unless compressing it heats it and loads it with water vapour, which condenses when you expel it. i.e. creating a greater temperature difference between mouth and environment.