Rainbows from flames.

[cladking]

Tough question here. I believe an ancient source claims that under ideal conditions, mist and otherwise total darkness, that rainbows can be seen refracted from burning willow tree oil. The best I can determine this oil would provide a full stectum, but I have doubt it would be sufficiently bright to see a rainbow. The flame would have been about 20' from the mist probably.

 

Am I wrong? Does anyone have any experience with this or know the equations? There is some chance it was a different type of oil but the only identifiable alternatives are olive oil or castor oil. The lamp had about a 2" diameter wick and probably small amounts of water with fuel flow.

[dimreepr]

This is very informative on the subject.

[cladking]

This is very informative on the subject.

 

Thanks, but as near as I can tell this is just a primer on the nature of rainbows. I could have missed a section on rainbows generated by flames but skimmed it pretty closely.

 

I assume by your linking this that you believe a rainbow would be visible because all the conditions are met? Do you have any experience with this? I consider a correct answer to be extremely important and lack the resources to duplicate the experiment. It's hardly life or death that the answer is correct but I need an unambiguous educated opinion because I don't trust my opinion on the subject (even though I could answer the questions posed).

Edited February 15, 2013 by cladking

[dimreepr]

I don’t have any direct experience but essentially all you need to create a rainbow is a light source and droplets of water. As for using flames, as a light source, it would depend on what you’re burning, I think the rainbow would skew towards the predominant wavelengths of the material being burnt. The lecture is worth a good look though, it goes into great depth and details all the conditions and types of rainbow, I have recognised aspects of, and different types of, rainbows which I mostly missed prior to watching.

[Enthalpy]

Just make the experiment with a light bulb. Preferibly small and round, like a halogen lamp.

 

Did I see rainbows made by car lamps? I believe so.

 

Intuitively, our eyes have such a dynamic range that replacing the strong Sunlight by a less strong flame light is acceptable, provided the surroundings are dark enough. It can require to intercept as well all indirect light from the flame diffused by the surroundings.

[cladking]

 

 

 

I don’t have any direct experience but essentially all you need to create a rainbow is a light source and droplets of water. As for using flames, as a light source, it would depend on what you’re burning, I think the rainbow would skew towards the predominant wavelengths of the material being burnt. The lecture is worth a good look though, it goes into great depth and details all the conditions and types of rainbow, I have recognised aspects of, and different types of, rainbows which I mostly missed prior to watching.

 

 

 

 

Thanks again.

 

Obviously with low light levels as from an oil lamp you'll need to worry about reflected light and I hadn't thought of this. It is very important that this be factored in.

 

I suspect this oil was used because it burns pretty brightly. I believe one of these lamps was found in the Tomb of Sabu from 3200 BC and is misinterpreted as a "tri-lobed bowl". A lot of the information I need is exceedingly difficult to find on the net. Some might not really exist and would need to be duplicated.