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Summer nights… July 2, 2017

Posted by WorldbyStorm in Uncategorized.
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I’ve always, since a kid, loved the long evenings in Summer and found the point at which we past midsummer when the nights begin to shorten kind of melancholy. That was this last week for those keeping note. Not that there’s much of a hit at the moment…. a week or so later the difference is as the linked chart demonstrates about a minute or so – and sunset is about 21.56. Mind you it moves fast, by mid July it’s 21.45 but by the end of July it’s 21.21. By the end of August we’re talking 20.16. By the end of September 19.03. And so on.

Speaking of summer nights, this is fascinating, a phenomenon known as ‘nocturnal nights’ where ambient light is sufficiently bright to read a book. Not that we’d know about it because of general human produced light at night.

In 1991, Shepherd built a satellite instrument capable of measuring airglow, which results when ultraviolet radiation from the sun separates molecular oxygen into individual atoms. The atoms recombine at night, once the sun disappears, releasing energy that emits a green tint.
His latest study came about after researchers noticed that, at times, airglow could be seen by the naked eye. Along with York University’s Young-Min Cho, Shepherd carried out an analysis of two years’ worth of satellite data, finding that wavelengths in the upper atmosphere were at times superimposed over each other, brightening the airglow by as much as tenfold.
Their analysis showed these bright nights occurred 7% of the time and were highly localised, confined to an area about the size of Europe. But outside of remote areas, chances of seeing an event nowadays are slim, due to widespread light pollution.

Sounds amazing.

I’m up in Donegal next month and hope the nights are clear to get a good look at the night sky. But even there, and I’ll be a short way north of Dungloe and just short of Burtonport, there’s a huge amount of light pollution.

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