Physics
OpenStudy (anonymous):

I am looking for an explanation of why clouds are white--other than "because they scatter all wavelengths of sunlight equally." Which is true. So is "the cloud droplet is too big compare to the wavelength." I would like to know what is happening at the subatomic level with scattering by cloud droplets-are wavelengths "bouncing" off droplets or is there something happening within the droplet/water molecule/atom. How does what is happening within a raindrop to create a rainbow compare to what is happening within a smaller cloud droplet? Help!

OpenStudy (jamesj):

Here's a lecture that answers many of those questions: http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/lecture-31-rainbows/

OpenStudy (anonymous):

Thanks for this terrific link to MIT Open Courseware. I watched the video lecture about rainbows, learned much, but Prof Lewin is talking geometry and I am afraid I need information on what is happening within the droplets of water at the subatomic level. I appreciate your help. The OCW site includes lecture notes on the physics of radiation and scattering, but not a layperson's level. I will keep looking for an answer!

OpenStudy (jamesj):

I'm confused. What is going on at a sub-atomic level is beyond the scope of first year Physics (of which the MIT lectures in 8.02 are part). And yet you want something at a lay-person's level?

OpenStudy (anonymous):

Hi--yes this is what I want. I am not a student but a writer of books on natural history. I am currently writing one on clouds and am deconstructing the dictionary definition of a cloud, which includes the fact that they are visible. Which puts me into their whiteness. I write for the lay audience which, in this case, means getting into the subatomic particles so that I can offer something more than "particles larger that 10 microns scattering white light unselectively." This really doesn't explain anything but is what is offered in the into chemistry and meteorology texts. I have been searching for weeks to find a ready-made explanation...but cannot find one. I believe I am looking for the mechanics of interaction (or so a friend tells me!).

OpenStudy (anonymous):

Adding a clarification and question: It looks like I need to understand the mechanics of the interaction between the photons in the visible light and the electrons in the atoms within the water molecule...to whom would I direct a question about quantized energy levels for visible light and water as it relates to scattering?