Birth of a sunset..again


Yes, I know I have done this before and apologies if you know the science, but this summer there were an unusually large amount of pretty decent sunsets to snap around here so I have a pretty full card of them and this was one of the best of the bunch.

True, many people like sunsets, but I have heard many of those look at a nice clear day and remark “going to be a nice sunset today”…no, it’s not, where’s the colour? Where’s the reflection from the clouds? If you don’t have that, it’s hardly even worth looking at to be honest. What follows below is the my definition of a nice sunset!

Firstly, you have to have a few bits and bobs of clouds waaaaay up there. They catch the colors of the sun as it gets very low and turns into the pinky reddy hues, but more about that later…

Ooooh, a good candidate for a nice sunset...

Ooooh, a good candidate for a nice sunset…

Moving on, this stuff up there in the sky needs to stick around, if there’s a wind and it’s blowing away your cirrus (very high cloud), this is bad news as there will be nothing way up for the colours to reflect from. However, if there is a mix of high and low as per my example, that’s even better, as there are lots for the colour to reflect from…

Sun just touching the horizon and the colours starting to scatter....

Sun just touching the horizon and the colours starting to scatter….

Time rattles by and those pink and reds come into play, this is where one of the few pieces of atmospheric science I know that I can quote (I have actually passed this on to a couple of fellow photographers when taking pictures, as most people pack up as soon as the sun dips below the horizon; I encourage them to stay and I hope they are glad they did).

Because the sun is low on the horizon, sunlight passes through more air at sunset (and sunrise, but I’m in bed). More atmosphere means more molecules to scatter the violet and blue light away from your eyes. If the path is long enough, all of the blue and violet light scatters out of your line of sight. The other colours continue on their way to your eyes. Because reds and such have the longest wavelength of any visible light, the sun is red when it’s on the horizon, where its extremely long path through the atmosphere blocks all other colours…and as it travels below the line of the horizon it can get redder and project this onto those lovely high(er) clouds to produce an effect such as those following. From this……

And the pink arrives!

And the pink arrives!

…to this, in 9 minutes.

Now that's a sunset, nice curvy bases to the reflecting clouds too, very nice

Now that’s a sunset, nice curvy bases to the reflecting clouds too, very nice

They are my favourite type of sunsets. Don’t get me wrong, I like them all, but I do love the red ones…have a picture of one on my phone at the minute too!

Now I can’t make this post all about one sunset sitting can I? So, for all of those who have stuck with me, here’s a double rainbow just for you…

next time you see a rainbow, look for the inverted colours and Alexanders Band

next time you see a rainbow, look for the inverted colours and Alexanders Band

For those who loooove de science, please refer to the extract for Mr Wikipedia;

Secondary rainbows are caused by a double reflection of sunlight inside the raindrops. As a result of the second reflection, the colours of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside. The secondary rainbow is fainter than the primary because more light escapes from two reflections compared to one and because the rainbow itself is spread over a greater area of the sky. The dark area of unlit sky lying between the primary and secondary bows is called Alexanders Band, after Alexander of Aphrodisias who first described it.

Now, I never knew any of that, so I hope you learnt something! It made me look at my picture harder and it does indeed have the colour inversion which I had never noticed before. Fascinating!

Right, that’s the lot for today. Next time NO SUNSETS, honest..I promise, I have few other subjects up in the hills I took pictures of that I will share. Thanks for stopping by and see you soon.


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