… is over. At least if you define the end of the polar night as the day on which ‘civil twilight’ returns at noon, i.e. the sun is 6 degrees or more below the horizon. This was the case yesterday (30 January) at just after 12 noon for the first time since 11 November.
Twilight: civil, nautical, astronomical
When the sun is lower than -6 degrees around the clock (i.e. 6 degrees below the horizon), this is called polar night. Before and after this, there are several weeks when the sun does not rise, but is very low below the horizon at midday (between 0 and 6 degrees), so that there is a clear twilight. This is known as ‘civil twilight’, which people experience as dawn. There is also nautical twilight (the sun is 6-12 degrees below the horizon, which can still be seen by navigators at sea) and astronomical twilight (the sun is 12-18 degrees below the horizon, which can still be seen by astronomers with a trained eye), and only when the sun is lower than 18 degrees below the horizon do we officially speak of darkness.
In Longyearbyen, it does never happen that the sun is lower than 18 degrees below the horizon for 24 hours. Even at the darkest time, around 21 December, the sun is still between 11 and 12 degrees below the horizon at midday, so that when the sky is clear there is a hint of twilight to the south. Strictly speaking, it is never completely dark for 24 hours in Longyearbyen.
The end of the polar night: view of Hiorthfjellet on 30 January, spiced up with a dose of red light (Rayleigh-scattering).
A few impressions from yesterday (30 January) at noon, although I had already missed the brightest point. There was indeed a good whiff of that wonderful red light in the air again, although it wasn’t as intense as it was a week ago.
Click on thumbnail to open an enlarged version of the specific photo.
Red light
I need to come back to the stunning phenomenon of the red light again. Firstly, in last week’s post (‘Red sky’) I somehow forgot to mention the name of the phenomenon that is ultimately responsible for this red light. It is called Rayleigh scattering. That should be added.
And I also captured the red light in a complete 360 degree panorama last week, it just had to be processed first. Here is an example from Adventdalen, at ‘Jernsenga’ (‘the iron bed’, there is indeed a bedstead standing in the landscape. But that is another story, for another day). There is another red light pano on the Innerhytta page, taken on a pingo a little further into Adventdalen.