What causes a red rainbow?

  • 3 Replies
  • 518 Views

0 Members and 1 Guest are viewing this topic.

*

Offline thedoc

  • Forum Admin
  • Administrator
  • Sr. Member
  • *****
  • 513
    • View Profile
What causes a red rainbow?
« on: 31/08/2016 17:23:02 »
Anthony leyland asked the Naked Scientists:
   A few days ago, just after sun down, we saw a pure red rainbow. I never knew these existed. I assume it's  down to the same reason we have red sunsets - that red light gets scattered less by the atmosphere. But I'd appreciate a more educated explanation!!
Thanks
What do you think?
« Last Edit: 31/08/2016 17:23:02 by _system »

*

Offline RD

  • Neilep Level Member
  • ******
  • 8171
    • View Profile
Re: What causes a red rainbow?
« Reply #1 on: 31/08/2016 18:05:54 »
Same reason as the orangey rainbows, see ... http://www.thenakedscientists.com/forum/index.php?topic=18551.0  [reply #9]

If the sun had actually set the red rainbow would arc very high in the sky

[ A recent one in the UK ... http://www.telegraph.co.uk/news/2016/08/25/spectacular-red-rainbow-illuminates-historic-english-town--in-ph/ ]
« Last Edit: 31/08/2016 18:23:01 by RD »

*

Offline VanVinci

  • First timers
  • *
  • 4
    • View Profile
Re: What causes a red rainbow?
« Reply #2 on: 02/09/2016 05:53:16 »
Anthony leyland asked the Naked Scientists:
   A few days ago, just after sun down, we saw a pure red rainbow. I never knew these existed. I assume it's  down to the same reason we have red sunsets - that red light gets scattered less by the atmosphere. But I'd appreciate a more educated explanation!!
Thanks
What do you think?

Not so much down to the same reason but rather a result of a red sunset.

A rainbow is produced by raindrops functioning exactly like Newton's Prism.

Light enters the sunny side of a raindrop and is refracted or bent by doing so.

It then reflects off of the back inner wall of the raindrop and refracts a second time as it passes back out of the sunny side of the drop.

Newton discovered that a Prism will refract light of different wave-lengths by different angles. Resulting in 'White Light' fanning out into the ROYGBIV spectrum we all recognize.

So what happens when you only start with light of Red Wave-lengths???

:)

*

Offline Colin2B

  • Global Moderator
  • Neilep Level Member
  • *****
  • 2029
    • View Profile
Re: What causes a red rainbow?
« Reply #3 on: 02/09/2016 08:19:35 »
So what happens when you only start with light of Red Wave-lengths???
If red's all you' e got, then red's all you'll get [:)]
and the misguided shall lead the gullible,
the feebleminded have inherited the earth.