Why does smoke appear to stick to a surface?

Discussion in 'Science and Nature' started by eldude-arino, Jan 18, 2014.

  1. We're sitting around the table this morning and a friend notices some smoke "sticking" to the table. Not the first time I've noticed it, but he acted as if he thought a ghost was trying to manifest itself. After some half-assed googleing, I found nothing:
    Does anyone know the effect I'm referring to, how it occurs, and what it's called? Guessing something to do with the density of the smoke.

  2. Smoke is very sticky.
    Sometimes in old houses the walls turn yellow from smoking

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  3. #3 4shotmark, Jan 18, 2014
    Last edited by a moderator: Jan 18, 2014
    True, but I think OP is talking about something else.
    He's talking about the property of smoke that allows you to do tricks like waterfalls and spills onto a table or book. I've wondered this too, but it has to just be an airflow and temperature thing. It works better with non-inhaled smoke, like shisha hits. This is an air physics question.
  4. Its the same reason if you spill water you will see streams and waterfalls instead of a perfectly shaped pool

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  5. I think it's because the intermolecualr attraction of the compounds in the smoke is probably stronger with the wood compared to the smoke to smoke compound.s  Like how water in a tube you'll see how it makes a concave. while something like mercury will have a stronger intermolecular attraction with other mercury atoms compared to the glass , which will appear convex .
  6. Temperature and density of the air and smoke are probably the biggest factors.. but I don't know of any scientific terms to describe it. When its warmer and less dense, it'll rise. When it's cooler and more dense, it'll sink. I had a parent growing up that would smoke indoors with the windows shut. It'd fill up the room, but there were times where it was a lot and it'd cool down and sink. So sometimes I'd walk in there and it'd seem like someone was running a fog machine, a leveled layer of smoke would just be sitting in the room. It clings just like most everything else does. You get blasted with a shot of water, chances are you're going to get wet. It's not like you're water repellant. Same when you get hit with smoke, particles inside the smoke will cling to you because you're not smoke repellant. Don't know the specifics, but like Jay said, probably has to do with intermolecular actions. The smoke cooled to where it's density is less than the air around it and was "pushed down" to the table. Probably acted like a pool of water too. Where the molecules that are above the layer of molecules that are clinging have a harder time clinging to fresh spots on the table. Like when a drip of water runs down, the next drop will want to follow it's course as it'll be the path of least resistance due to a molecular layer being laid.
  7. #7 PeterParker, Jan 19, 2014
    Last edited by a moderator: Jan 19, 2014
    Yea definitely temperature & density, for the following specific reasons. Cool air is less "active", since heat energy is motion, comparatively warmer air has molecules moving around more quickly then cooler air. So there would be a point where the air molecules don't have enough kinetic energy to push the smoke particles around. And those smoke particles  are heavier so tend to "sink" in air and land on a table or floor for example. I'd guess that it's about the comparative temperatures, such as the smoke particles being the same temp as the cooler air.
    Also the "buoyancy" or how dense the air is matters & probably most since the more visible smoke particles maybe too heavy to be pushed quickly with typical room temps temperatures. So buoyancy matters as far as the smoke particles being able to "float", a perfect balance of sorts.
    This is an example of Brownian motion, Einstein used this to prove the existence of atoms & I think light quanta (photons). This perspective of thinking may have led him to the photoelectric effect for which he won a noble prize (among other reasons).
    So maybe it could be said smoke doesn't rise, but hotter air does and puts air particles in motion by the difference in air density which in turn constantly bombard the heavier smoke molecules pushing them up. 
    Which is interesting because one of the best examples of the photoelectric effect is photosynthesis, which we all love!
    So boom bared those plants with heaps of photons of a particular energy. Yay Brownian motion -> photoelectric effect -> photosynthesis -> cannabis -> high -> cool slow motion smoke
    Brownian Motion Smoke demonstration  & Another more clear example done with water by a REALLY enthusiastic guy
    In oxygenic photosynthesis water is the electron donor and, since its hydrolysis releases oxygen, the equation for this process is:
    2n CO[SUB]2[/SUB] + 4n H[SUB]2[/SUB]O + photons → 2(CH[SUB]2[/SUB]O)[SUB]n[/SUB] + 2n O[SUB]2[/SUB] + 2n H[SUB]2[/SUB]O carbon dioxide + water + light energy → carbohydrate + oxygen + water
  8. Smoke sticks to walls because the smoke contains chemicals that.... stick to walls. In particular the smoke from a cigarette. 
  9. If you're in a warmer atmosphere with little to no airflow then you'll most likely get smoke that wants to linger. Especially around other surfaces that are cold. Sent from my iPhone using Grasscity Forum

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