How many hours of darkness in a year

By: Tony Flanders July 19, 0. You can unsubscribe anytime. No matter where in the world you live, do you get the same number of daylight hours over the course of a year? Approximately kilometres from Oslo, Rjukan is one of the most singular places in the world. Its natural beauty is also its worst feature, since it is because of this geographical location that Rjukan does not receive a single drop of sunlight for 6 months of the year.

From September to March the mountains make it impossible for the rays of sun. But this situation changed a couple of years ago. After a century spending six months of the year in semi-darkness, in , 3 heliostat mirrors were installed, which move and rotate on a specific axis, to capture the sunlight. Its tracking system enables them to track the sun depending on the height thereof and reflect sunlight downwards to the main square, where the inhabitants of Rjukan can feel a little bit of sun on their faces while they chat to their neighbours.

We return to North America to visit Barrow, located in the extreme north point of Alaska. It is the most northerly point of the Unites States and a significant geographical landmark, marking the limits between two of the marginal seas of the Arctic Ocean: the Chukchi and the Beaufort. Barrow can go two months without seeing any sunlight , because it is located just a few hundred kilometres from the Arctic Polar Circle.

Here, in the middle of the North Atlantic, between the Scottish coast and Iceland, is an archipelago battered by strong winds and where fog and cloudy skies are commonplace.

It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. It seems intuitively obvious that the amount of daylight per annum should be the same for any latitude on earth.

For example, 12 hours per day at the equator. The poles have daylight for half the year and darkness for the other half crudely. Is there any way to get an answer to this apparently simple question - is the annual amount of daylight the same at any point on earth?

The naive expectation is that, for every place on Earth, the Sun will appear to be above the horizon for exactly half the time. Thus, for a standard year consisting of hours, apparent maximal daytime duration would be hours. However, there are physical and astronomical effects which change that picture. Namely, atmospheric refraction allows the Sun to be still visible even when it physically sets below the horizon line.

For that reason, average daytime disregarding cloud effects is longest in polar areas, where the apparent Sun spends the most time around the horizon. Alaska has won world records for their pound rutabaga and pound cabbage. Another thing to consider is supply and demand. Produce is very expensive to import from out of state, so innovative farmers are using land that is either rich from volcanic soil or greenhouses to grow year-round. Alaska and many other northern parts of the world experience long periods of twilight.

During civil twilight, the sun is less than 6 degrees beneath the horizon. Lastly, at 18 degrees, is astronomical twilight.