Naked Science Forum

Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: neilep on 21/01/2008 19:22:35

Title: Purple Mountains ???
Post by: neilep on 21/01/2008 19:22:35

Hi I'm Prince,

In 1984 I starred in the movie and sang my song Purple Rain !!

Now, why on Earth did I not sing about Purple Mountains like these !!?

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I think I know the answer....cos at that time ...I had no one to tell me the reason why these mountains look purple !!..I mean why are they Purple ?





"Oh Purple Mountain, Purple Mountain !!"

....hmmmmm.....I think I was best to stay with 'Purple Rain' !!

Title: Purple Mountains ???
Post by: Karen W. on 21/01/2008 19:53:35

          America!


OH beautiful.... for spacious skies.. for amber waves of grain....... for purple mountains majesty.... above the fruit and grain....... America America God shed his grace on thee... and crown thy good with brotherhood... from sea to shining sea!!! [;D] [;D]

Perhaps the light catches the mountain at a certain angle at a certain time of day making the bluer skies reflect more of the suns red light making it more of a purple as it is reflected onto the surface below! I am no good at guessing these things.. but surely it has to do with the refraction of light somehow!

It is very lovely!

Title: Purple Mountains ???
Post by: JimBob on 21/01/2008 21:36:06

Essentially correct. The earth's atmosphere acts as a prism at dawn and dusk, separating sunlight into it's component parts. The blue is most prevalent at dawn, red added to the atmosphere at dusk.

Title: Purple Mountains ???
Post by: neilep on 21/01/2008 22:24:48

I ask and an answer is forthcoming !!

THANK YOU to Karen and to JIMBOB.


Your responses are welcomed and appreciated !!

Title: Purple Mountains ???
Post by: Karen W. on 21/01/2008 23:46:43

Your welcome and I am shocked to even be in the right ball park with an answer... You guys just be rubbing off on me thats all.... LOL... Thanks  JimBob..

Title: Purple Mountains ???
Post by: rosalind dna on 23/01/2008 12:04:39

That is just what I was thinking that mountains become purple at Sunrise or
late Sunset. I have never seen those mountains.

By the way, a beautiful photo. thanks

Title: Purple Mountains ???
Post by: daveshorts on 23/01/2008 16:32:34

Quote from: JimBob on 21/01/2008 21:36:06

Essentially correct. The earth's atmosphere acts as a prism at dawn and dusk, separating sunlight into it's component parts. The blue is most prevalent at dawn, red added to the atmosphere at dusk.

Although the atmosphere can act as a prism, It certainly doesn't work like this. Morning and evening are pretty much identical barring a bit more dust and moisture in the evening. The prism effect is only really noticible right as the sun sets when it can go a strange shape, and very very rarely there can be a green flash just as the sun sets.

 It is more to do with the scattering of light eg.
http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/why-is-the-sky-blue/

so at sunset you will get direct light which is predominantly red, and scattered light from the sky which is blue. Red + Blue = purple.

Title: Purple Mountains ???
Post by: moonfire on 24/01/2008 13:59:48

I was just viewing some mountains this past week being out of town.  The ones closest to us had no snowcaps, but the ones further away that I was viewing through binoculars had caps of snow.  I also, noticed the colour of some were gray and some were brown.  Why? Also, they were along the same line with the colour changes...