How does being in a polar region affect the golden and blue hours of light?

Question

While I already know what the golden and blue hour are, I am having trouble understanding how this changes very close to the poles so that I can time an upcoming trip to Iceland.

Online services give different interpretations which make little sense. Here is a screencap from Twilight Calculator. Note how the sunset and sunrise time increase consistently and so does the corresponding Golden hour and Twighlight duration until May 16th. On May 17th things get weird. The golden hour duration jumps from 122 mins the previous day to 309 mins. 309 mins!

• Does that mean the sun stays above the horizon the whole night? In which case, it should be all golden and none blue.
• Or does the sun dip below the horizon? As suggested by the fact there there is a sunset and sunrise time and therefore. And therefore should there not be about 305 mins of blue hour? ...and the golden hour should last about 87 mins?
• Should the last two columns in that chart be reversed starting on May 17th?

Given that I am looking to Iceland for mostly landscape shooting, the big question is: When would there be the most golden light? (So when the sun is above the horizon and not below).

Answer 1

Iceland is so far north that depending where you are in the country, you get significantly different results. Compare the following chart from gaisma.com for Reykjavík, which is in the south:

With this chart, for Ísafjörður in the north:

As you can see, between mid June and the beginning of July, the sun never actually sets in the north of Iceland, however in Reykjavík it DOES set, but it stays light enough to remain twilight throughout sundown (the pink area). At this latitude, there would be little to no 'blue hour' as it rarely gets dark enough, even in Reykjavík.

To answer your final question, the best time to go for as much golden hour as possible would be between mid May and late July, as this is when you get the most twilight (as much as 5 hours), and as it occurs in the early hours of the morning, you will not be competing with tourists for the best scenes.

Note that as Iceland is not on the meridian, but uses GMT throughout the year, the sun's lowest point occurs at around 1:30 am, not midnight, so you can still get 'midnight sun' in Reykjavík around the summer solstice, even though the sun does eventually set (around 12:05 am).

Oh, and have a great time. Iceland is a wonderful country!

Answer 2

Here is a screenshot from TPE. Normally this would show the following:

• Sunset - the time the sun sets

• Civil twilight - defined as when the sun is below the horizon, less than 6 degrees - brightest stars and planets visible

• Nautical twilight - defined as when the sun is between 6 and 12 degrees below the horizon - many more stars visible

• Astronomical twilight - when the sun is between 12-18 degrees - effectively this is completely dark

And the same things are reversed at sunrise. Twilight is the period after the sun sets, when it is below the horizon, but the sky is not yet dark (or the same period before the sun rises) Civil, nautical and astronomical are increasingly darker (civil = looks dark for driving, nautical = dark enough to navigate from most stars, astronomical = dark enough for most astronomical viewing)

You'll see that nautical and astronomical figures aren't visible, so the sun must not get more than 6 degrees below the horizon.

Nothing magical happens on the 18th. Sun sets about 10:45pm and rises around 4am. But once it sets, it's just below the horizon and the sky will not be completely dark - you'll only see a few of the brightest stars. I would imagine the sky would be no darker than a dark blue.

At the equator, the sun rises and sets very quickly. When it sets, it gets dark pretty fast. This is because it rises very near due east, crosses the entire sky and sets nearly due west, and the day is roughly 12 hours. Nearer the poles, the sun rises more slowly. The sun will rise in the northeast and set in the northwest. So it only covers a much shorter distance in the sky over what is a much longer day than the equator (18 hours!). So it appears to move much more slowly across the sky, and this includes sunrise and sunset.

In most parts of the world, the time between sunset and civil twilight is 15 minutes to a half hour. As you can see, for Rykjavik, it's almost 2 hours. Two hours for the sun to go from 6 degrees below the horizon to the horizon. It will take a similar time to rise 6 degrees above the horizon. So you should get long, slow sunrises and sunsets and plenty of blue and golden hours.

Compare that to the equator, where the sun covers 180 degress in 12 hours, or 15 degrees per hour. In Iceland in May, more like 6 degrees in 2 hours. Quite a difference.

After May 17th, the sun will continue to set later and rise earlier, until the summer solstice around June 21st.

Answer 3

I don't know about Iceland, but I do know that in Alert (which is now a weather station in Nunavut, but was the northernmost Canadian Forces Station where we listened to the Soviets at the times I was there), you did run into periods where the sun either never rose at all (close to the winter solstice) or never dipped below the horizon (close to the summer solstice). It's only the period centred around the equinoxes when you get the full range of daytime/nighttime.

As you approach the summer solstice, you will hit a point where the sun never actually disappears below the horizon (the top of the solar disk will still be visible). From that point until the solstice, the minimum height of the sun above the horizon increases from day to day, then it decreases again until the sun finally dips below the horizon some days or weeks after the solstice. So lots of Golden Hour shooting time (yay!) but lots of weird disturbances to your circadian rhythms (boo!). If you've never experienced it before, you can spend a lot of days not sleeping at all unless you create a dark place (closing curtains, drawing blinds, etc.).