Illustration of the time zones of the world, where the earth is seen from the top (source).
The last week or so we have been doing bathymetric mapping surveys of the seabed in an area more west, close to Canada. We transited from the pole further south, to around 82°N 142°W, for these surveys. Transiting 7° south may not sound like much, but it is approximately 780 km (I wrote about the conversion between degrees and distances here). I was surprised by the noticeable difference in light.
I want to talk a bit about time zones and longitudes, which are actually a bit tricky up North. When you travel east and west in the world, depending on which longitude (breddegrad) you are on, there are different time zones. This is because night and day occur at different times in different places on Earth, due to Earths rotation. I assume most people are familiar with this. The first figure below illustrate the time zones of the world on a map of polar stereographic projection (the North Pole is in the middle, and the equator on the outer edge. I have another post coming up on maps can be tricky business in the Arctic.) You can see that the closer you get to the Pole, the closer are the lines/longitudes and therefore the time zones. Since the longitudes define the time zones, and the longitudes come together at the poles, the time zones in reality change a lot with small distances up here.
However, which time it really is, is impossible to tell. During summer, the Arctic has 24 hours of daylight (actually, it is mostly just white). Therefore, we could have chosen any time zone of the world without it having mattered it is just a matter of definition! The scientific team on the research cruise have decided to follow the Coordinated Universal Time, known as UTC, during the whole cruise. This is the time zone of London without Daylight Savings Time.
Another practical reason for choosing to use the same coordinated time is for scientific purposes. There are many scientists on board, and many are working together on different data. Therefore, it is practical that everyone is recording measurements on the same reference time for the whole cruise. Can you imagine the mess in the database if we were changing the time several times, back and forth?
Anyways, back to the point. As we were moving southwards, the bridge (where others and I usually sit and work during the day) got noticeably darker during the mornings. I did not realise until then that the time zone we were in (which was UTC -10 hours, so the time zone of Hawaii and French Polynesia) actually mattered. Since the time zone was 10 hours after our time, it meant that when our clock was 10:00, it was actually midnight, and we were far enough south to notice the difference. I would not exactly say it was dark, but for someone who has not experienced night in over a month it felt dark!
There is another fun consequence of all these longitudes and time zones coming together at the pole. After the expedition, when we are crossing back to Svalbard on the eastern side of the pole, is that I can say that I have been to every single time zone in the world!