Sunrise 2 days early?

Each winter the poles (North and South – during their own winters) have permanent night time. The angle of the Earth to the Sun prevents the Sun from rising at all.

The opposite happens in the summer – with permanent day light (even at “midnight”)

The movement of the planets is very predictable, so there are tables of sunset and sunrise times for everywhere.If anything changes this it must be on Earth. So people are worried that the sun rose 2 days early this year in the north, because it means something on Earth has caused it.

The atmosphere (like a prism) will bend (or PhysGeeks like me call it refract) light because of density changes. Oddly this means at “sunset” the Sun is actually already below the horizon – the atmosphere has bent the light so we can still see it.

Similarly sunrise the same can happen – so the atmosphere could be the cause of the early sunrise.

So – possible causes?

  • Tilt of the Earth changed? No – we’d see this by the stars at night being moved too.
  • Optical illusion?  Most likely – if the atmosphere had changed enough to bend the light more – temperature and a change in the gases – climate change
  • Lower land? Also likely – the ice caps are melting resulting in a lower horizon so the light gets through earlier – climate change

Worryingly the second and third option are more evidence of climate change -Greenland is now about 3 degress Celsuis above it’s average historic temperatures for much of the year.

Mr G

Sources: Livescience, Daily Mail

 

 

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2 comments on “Sunrise 2 days early?

  1. Why do the ice caps melting result in a lower hoizon? If there’s more water and less ice, surely the horizon will rise?

    • This is because in Greenland the ice is on the land, so as the ice melt the ice on top of the land reduces in height.

      The ice in the water will not raise sea levels as it melts, but a very large volume of ice in the poles is on land. When land ice melts the water flows into the sea raising the level.
      (the Arctic pole ice is floating ice with big chunks on land such as Greenland, but the Antarctic ice is on land)

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