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Frozen Planet: The all-night sunset

Updated Monday, 19th April 2010

As Spring arrives in Svalbard, Mark Brandon is treated to a six-hour sunset

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In only one day's time the sun will rise on the city I am staying in and it will not drop below the horizon until close to the end of August. This is the so-called polar day.

Usually, at low latitudes, the sun warms the environment up fairly quickly. Here, though, although it is above the horizon, it is still too low to be warming. You can see that in the plot I made below.

Average monthly temperatures at Svalbaard airport over 98 years - red dots showing the average. Copyrighted  image Icon Copyright: Mark Brandon

This shows the average monthly temperature at the airport (about a mile away from where I am typing this) for the last 98 years.

The y axis is the temperature in degrees Centigrade and the x axis the month (so “J” is January, “F” is February and so on).

Each green dot represents the average of one month, the red square is the average temperature for all of 98 years.

The red bars above and below the red square represent the range of temperature you should usually expect in that month.

So, for example, in January I should expect temperatures of about -15C, but anywhere from -11C to -20C shouldn’t be a surprise.

For the month we are in now, I should expect a temperature in the range -9 to -15C - and actually that is exactly where it has been.

At the moment it is -12C and I have the window to my room open and no radiator on. (It is so hot inside!)

All of this excludes wind chill though. These cold temperatures, plus a little bit of wind on exposed flesh, and you can damage yourself really rather quickly.

As the sun comes above the horizon the light it gives out is a little strange. In the middle of the day, you get the blue sky – as you would in the UK. However, after about 10pm, through to 4am, it is like getting a 6 hour sunset - because the sun is so low on the horizon. Beautiful.

You can see from my plot that next month, as the sun gets higher in the sky, the air temperature will start to rapidly warm; by June it will be above freezing. That brings its own problems because then snow disappears - and the ground can start to melt.

For me winter and early spring are the best!

Find out more

Discover how to make an accurate clock using the sun

Janet Sumner explains how Britain was shaped by ice

Sunset in Lapland Creative commons image Icon Sami Keinänen under CC-BY-SA licence under Creative-Commons license
Sunset elsewhere in the Arctic Circle: The sun sets on Lapland





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