giovedì 9 giugno 2011

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The Splendour of Sunsets

What can be more emotive and striking to the senses then that magical moment ,  when the fading glory of the sun disappears below the horizon, at sunset ? Not that the image you see is real, for the air itself, through refraction of light, creates a mirage in which we believe we see the sun slipping below the horizon, but in fact it has already been there for some minutes.

We should remember, also, that sunset and dusk are different animals, dusk being when darkness actually falls, after a period of twilight. There is no doubt that anyone could wax lyrical about the incredible beauty of the rainbow colors that are always in evidence at this most spectacular time of day, all due to what is known as atmospheric defraction.

This is the process by which rays of light from the sun, or indeed magnetic waves, are made to alter their paths through the atmosphere by the varying densities of air that they encounter. The intensity of the various rainbow colors seems to be magnified at this time of day, the reds and oranges, greens and blues seeming much more vibrant than usual.

This may be due to the scattering of the light rays mentioned earlier, throughout the layers of the atmosphere, because the particles which create the scattering effect are of differing sizes and wavelengths.

Sometimes, with particular regard to light rays, the process is referred to as the Rayliegh Scattering, after the scvientist who first discovered it.  When it comes to the movement of light through gases, shorter wavelength colors are scattered more.

This means that violet and blue are much more widely dispersed than yellow and red light,  so the more particles there are in the atmosphere at the time, the more dramatic and pronounced are the displays of colour that this amazing  natural light show produces.

Sunset invariably brings an extra intensity to this spectacle than does sunrise, simply because the required particulates are much more in evidence at that time in the day. There is little doubt that the physics of this phenomenon, whilst interesting, do little to really describe the incredible beauty of it in the sky, and every day has a uniqueness to it, akin to the human fingerprint, for no two sunsets could ever be the same, just as the conditions of the atmosphere above us must vary from moment to moment.

There may be those who wonder how sunsets must appear on other planets, and we can show one from Mars, but the lack of real atmosphere inevitably means a lack of colour, so they can never be as wonderful as the sunsets we experience here on earth. Nature loves to show off, at certain times of day, and we should be thankful that such glorious sights are ours to enjoy, absolutely free. Long may it continue to be possible.


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