Friday, 12 October 2012

Twilight...Good or Bad?

A few weeks ago I wrote about how Autumn was starting to show its hand and Christmas is on it way, heralded by the beginning of a new series of Strictly Come Dancing on the ridiculously pantomimed X Factor live shows. Well autumn is now with us. It was a bright sunny day today however the wind had a real chill in it. This morning was the first one where I wished that I had put a coat on. I had cause to stand outside this afternoon and although I was standing in bright sunshine it still felt chilly.

The nights are also getting darker and it will soon be time for the clocks to turn back to GMT. Tonight driving home it was starting to get dark and it reached that level of darkness where it is difficult to see. This is the time when turning on the car headlights seems to make no difference to seeing the road ahead. One minute I find myself struggling to see because of the dimming light, the next I go round a bend in the road and can't see because the setting Sun is blinding me.

http://vt-2004.astro.cz/fotogalerie/www.vt-2004.org/photos/images/vt-photo-02-tl.jpg

I believe that this time of the day is known as twilight, the period of the evening during daylight and darkness or the light from the sky caused by the reelection of the Suns rays from the atmosphere. Apparently twilight also occurs in the morning between dawn and sunrise. The length of time for twilight varies depending on latitude; as long as two hours for the arctic and as short as thirty minutes for the equator. Apparently the twilight observed by Curiosity on Mars lasts comparatively longer due to dust in the Martian upper atmosphere scattering light to the shadow side of the planet. Interesting. For most younger people the word twilight means something to do with teenage vampires, I'm really out of touch with that one!

Soon we will get to that time of the year when I don't see the house in the week in the light, arriving and departing in the hours of darkness. Both twilights will happen whilst I'm at work. I find that a little depressing, but I guess it also means Christmas is getting closer.

 

1 comment:

  1. What is the difference between twilight and dusk Ed?

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