Rainbows and Brilliant Arches

update, addendum

Last week’s astro club meeting was about… as you have guessed, rainbows and arches created by ice crystals. Now, I know it has nothing to do with stars and planets, but hey, the atmosphere is above us, so… Anyways, the bulk of the meeting could be described in the following video:


Vodpod videos no longer available.



By the way, about the secondary arc stuff, there is also tertiar, quartenary, etc etc etc. The thing is, each arc decreases in brightness as they reflect and escape inside the raindrop. Also, the third, fourth, seventh, eight, etc are in the sun, and most people don’t look towards the sun when looking for bow. The limit for human eye may be third, who knows, maybe there is a way to see or photograph the third one, but there is none yet. So, I don’t know if there could be a way to see it, though the astro club presenter did suggest an experiment to see it.

Also, if you think that the rainbow actually touch some part of the land or something, you are wrong. So wrong that you don’t even deserve to have a peek at this web site. Seriously, you are really wrong. The rainbow is a product of your mind, an optical illusion, and there is no measurement of its distance. It is only measured in degrees. Therefore, it can be of any “size” (there really is no size, since it is from your mind), but it will always be an angular size between 40 to 42 degrees.

Of course, there were other things that were not in the lecture above. In a rainbow, if the raindrop is really small, then something called the supernumenaries will appear, meaning multiple rainbow in the same arc. If it is large, it will flatten into a spheroid (no, most raindrops are spheres, not tear drops) and it will cause the bottom part of the rainbow to get fat.

(Not the real shape of raindrops)

                                                                                             (Note the order of color, the two arcs, and the really bright white interior)


 (Moonbow!! It is very rare, click on it)

                                                             (Cicumhorizontal arc! Happens with high cirrhus clouds. If you say rainbow, I will hang you with your own intestines)

How about a whole lotta phenomena, including sun dogs, upper and lower tangental arc, circumhorizontal arc, circumzenithal arc, halos together! Just click the pic. There are a whole lot more pics of various arches in the web page, and their explanations, which has to do with ice crystals, so check it out!

Other lights and shadow phenomena:

The sun column, happens when ice crystal plates stack up on top, it can happen with large artificial lights too:

For more on the anatomy of ice crystals and their reflections, go here, look at the side menu.

Finally, there is the various phenomena by water drops:

Cool stuff, wasn’t it? 🙂 By the way, next post will be on my next pop quizz, and you will be tested on certain rainbow configs which will seem weird, which may or may not be fake, and you will have to say why. All the knowledge in order to respond the questions will be on the lecture I posted, so pay attention!

I already posted the pop quizz, so why don’t you go there and try it out? ^_^

more about “How to Make Teaching Come Alive | MIT…“, posted with vodpod

2 Responses to Rainbows and Brilliant Arches

  1. […] https://ibyea.wordpress.com/2009/01/31/rainbows-and-brilliant-arches/ Possibly related posts: (automatically generated)OMFSM!!! EXOPLANETS!!!God’s Marblesfrom the depthsNo Title […]

  2. […] remember that post about rainbow, and how I told you I was going to quizz you about it? Well, this is it. Now, […]

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