Green Flash

[Mike Maunder]

There is a lot of confusion, certainly in the literature, about the Green Flash - how it happens and when seen.

For a long time now you will know about my banging on about the superb Alderney skies and why that happens due to laminar flow. This is where the atmosphere settles into stable distinct layers (mainly due to temperature, but not always).

In most books you will read that the Green Flash only occurs when the sun just dips below the horizon, and the best place to see that is said to be the tropics, but I've rarely seen it there - because the hot air causes turbulence as it rises &c. On Alderney the atmosphere gets air from vast distances out in the Atlantic at a much lower temperature and has plenty of time to settle into the layers we see here, particularly recently.

In the last week stars haven't twinkled & I've seen the Green Flash several times with a rather rare intense blue example (regrettably not photographed), not green that appeared text-book fashion as the sun had just dipped below the horizon.

Today the steady wind and low temperatures seemed set to see the much rarer phenomenon that's the common one here, namely multiple green flashes as the sun sets towards the horizon. My record is losing count after 30 as the sun sets through the layers, starting long before the sun's lower limb has reached the horizon. The effect is a mirage and optics analogous to fibre optics.

When you see the sun's sides breaking up into layers, like attached at 20.27, the scene is set to see many. Unfortunately clouds obscured any chance of seeing the "normal" effect, but the 20.33 shows the effect so common here where Green Flashes break away from the top. That breaking away and "staying there" explains some of the normal effect as the sun goes below horizon.

I used a 300mm fl lens on medium format digi camera with higher resolution so that the images seen here can be heavily cropped ~10% of original and still stand blowing up on your monitors/screens there.

If anyone wants to see the original jpgs sequence as the event unfolded, let me know and I'll chop down from ~17Mb originals.

Enjoy

Mike

--

Mike

Today's thought

"What we do in life echoes in eternity" - Russell Crowe said in Gladiator

[Tony Roberts]

I have of course never seen a green flash ( I expect you remember urban skies), but I have never seen an image of one either. Thank you for sharing this.

Dark skies, perfect seeing, I must make a point to come over. 

Website shows that scenery, hotels and food are equally impressive.  Are there any specialist "Astro hotels" on the island that offer hire of on site telescopes? Not sure I fancy excess baggage charge on scope and mount.

Tony Roberts

Sent from my iPad

--
You received this message because you are subscribed to the Google Groups "Altair_B" group.
To unsubscribe from this group and stop receiving emails from it, send an email to altair_b+u...@googlegroups.com.
To post to this group, send email to alta...@googlegroups.com.
Visit this group at https://groups.google.com/group/altair_b.
For more options, visit https://groups.google.com/d/optout.

<Multiple green flashes Alderney 2016.4.30.8.27BST.tif>

<Green flash 2016.4.30.20.33BST.tif>

[Michael Maunder]

Tony

As with parallel mail, need to answer in more detail - been working on the astro equipment issue on site here for reasons you say. Not easy, more of a question how to get here...

Mike

Sent from my iPad