Expert: Ed - 7/17/2006

Question
I was observing the lights of Christchurch NZ while awaiting my daughter tonight. The lights twinkled more near the sea than inland at the same distance from me and I presume that was to do with different density or movements of air (or layers of air) near the sea BUT I also noticed that the reflections of Sodium street lights, in a lake adjacent to them, didn't twinkle whereas the lights did. Is this something to do with polarised light being less affected by air differences?

Answer
Alan,
This is a fascinating question, but I need to do research of my own before being able to trust myself to give you an answer.  

Until then, you may wish to google the term "terrestrial scintillation" and see what you can turn up.  I suspect that the phenomenon you observe has more to do with localized atmospheric humidity patterns, particularly so as you actually mention the existence of nearby bodies of water in the text of your question.  I suspect that this is more likely to account for the discrepancies you observe than the difference between two kinds of light.

Could you ask me again in a week or so, when I've had some time to look into the matter more thoroughly?  In the meantime, the people mentioned in this article:
http://www.scienceblog.com/community/older/2004/9/20048063.shtml

have been doing work on topics closely related to your query.   If you wanted to e-mail one of them, in Berkeley, I imagine that they could help you more quickly than I.

If you wish to get back to me, you have to do it yourself.  The AllExperts website doesn't operate in such a way as to enable me to recontact you on my own.

Good luck with this, and Keep Looking Up!
--Ed