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Great Rainbow this evening.

Started by The Thing, Jun 11, 2019, 20:07:25

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The Thing

I hope Google lets you see these - the links I've used may not be correct.



Cloudy? ¯\_(ツ)_/¯ (Gallic shrug :))

MarkS


Carole

Wow.  The 2nd one really shows all the colours.

Carole

Hugh

Rainbows ~ one of natures wonders ~ yet they do not actually exist! 

In the top picture there seems to be a double rainbow?

Thanks ~ they always seem to cheer my day up!

Hugh   :D

ApophisAstros

Did you get to the "Skittles" at the end... :lol: :lol: :lol:
Roger
RedCat51,QHYCCD183,Atik460EX,EQ6-R.Tri-Band OSC,BaaderSII1,25" 4.5nm,Ha3.5nm,Oiii3.5nm.

Carole

#5
Any-one know the scientific reason why with rainbows the sky is darker one side of it than the other?

Carole

The Thing

Quote from: Apophis on Jun 12, 2019, 11:01:49
Did you get to the "Skittles" at the end... :lol: :lol: :lol:
Roger
No but there's a farmer with a Merc at the left hand end. Probably a pot of EU subsidies buried there!
Cloudy? ¯\_(ツ)_/¯ (Gallic shrug :))

Hugh

Carole

Courtesy of Wiki.

The sky inside a primary rainbow is brighter than the sky outside of the bow. This is because each raindrop is a sphere and it scatters light over an entire circular disc in the sky. The radius of the disc depends on the wavelength of light, with red light being scattered over a larger angle than blue light. Over most of the disc, scattered light at all wavelengths overlaps, resulting in white light which brightens the sky. At the edge, the wavelength dependence of the scattering gives rise to the rainbow.

Also, apparently, the banding we see is an artefact of human colour vision with it being a smooth transition in reality ~ there is no banding visible in a black and white photos.  Further, where there is a double rainbow, the colours are reversed in the second to the first.

All useful information for grandchildren!

Best

Hugh

MarkS

#8
Quote from: Carole
Any-one know the scientific reason why with rainbows the sky is darker one side of it than the other?

Carole

Within the circle formed by the primary rainbow, the rain droplets reflect some white light back to the observer, making that area look brighter. 
See here: https://www.atoptics.co.uk/rainbows/primcone.htm

However, between the primary and secondary, no light is reflected back, leading to Alexander's dark band.
See here: https://www.atoptics.co.uk/rainbows/adband.htm

Use the menu at the left hand side to find lots of other very interesting technical info on rainbows and other atmospheric phenomena.

Mark

Hugh

Thanks Mark

I love the fact that we each have our very own rainbow ~ how special is that!

(Each person has their own cone and sees their very own rainbow).  Second link above.

Hugh

Carole

Thanks for that Mark, I found the second link easier to understand.

I did know that each person is seeing their own Rainbow, I think I learnt that possibly at school but I never learnt about Alexander's dark band.  I knew there must be a scientific explanation for it as it always seems to happen.

Carole