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Author Topic: Why does cigarette smoke form swirling patterns?  (Read 16381 times)

Offline AllenG

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Why does cigarette smoke form swirling patterns?
« on: 07/12/2008 22:44:20 »

Photo: David Barstow

What causes the complex swirls and lines in the smoke of a smoldering cigarette?
Why is fog so uniform while smoke seems to be more coherent?
« Last Edit: 08/12/2008 20:42:09 by chris »


 

Offline Chemistry4me

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Re: Why does cigarette smoke form swirling patterns?
« Reply #1 on: 08/12/2008 01:11:52 »
Maybe smoke contains many different particles of different sizes so some will move faster than others, while fog is just fine particles of water...
Just a stab in the dark.
 

Offline Don_1

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Re: Why does cigarette smoke form swirling patterns?
« Reply #2 on: 08/12/2008 07:35:50 »
The temperature and different rates of cooling of the particles and the different weights may have something to do with it, but air movements are doubtless the major factor.
 

Offline LeeE

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Re: Why does cigarette smoke form swirling patterns?
« Reply #3 on: 08/12/2008 17:12:46 »
I believe that it's down to two main factors; the homogeneity of the density and the scale of the turbulence.  The density of fog is relatively homogeneous, when compared with smoke, but there is also a large difference of scale.  There is similar turbulence in fog but because it's on a much larger scale you will only see a small region of it, where it will be relatively homogeneous, and then because the fog is more homogeneous anyway, those differences will be more difficult to see.
 

lyner

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Re: Why does cigarette smoke form swirling patterns?
« Reply #4 on: 08/12/2008 17:28:29 »
There is very little turbulence inside fog. It is a region of water droplets carried around in a very large system of turbulence - the Weather. Look at that from above and it's antics are just as involved as you get with curling smoke.
I think it's a matter of scale. The difference in the actual shapes formed by weather and smoke columns is probably to do with the effect of the viscosity of the air. There are very small forces involved with rising cigarette smoke, compared with the viscosity of the air whereas  viscosity plays a much smaller part in large air movements.

Air flow just doesn't 'scale', which is why bumble bees in flight look so unlikely.
 

Offline Soul Surfer

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Why does cigarette smoke form swirling patterns?
« Reply #5 on: 09/12/2008 09:25:45 »
It is a matter that the smoke particles only occupy a small volume of the air and clearly indicate details of the general airflow  you can see similar effects in the opposite direction by suapending s block of dry ice in still normally humid air and watching the fog descend from it so it is clearly not a significant propery of the nature if the particles.
 

lyner

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Why does cigarette smoke form swirling patterns?
« Reply #6 on: 09/12/2008 18:19:58 »
I agree; the particles are only indicators of what's going on.
 

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Why does cigarette smoke form swirling patterns?
« Reply #6 on: 09/12/2008 18:19:58 »

 

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