Unless you live close to the equator, you might have noticed that there are fewer hours of sunlight in the winter and more hours of sunlight in the summer. This is because of the tilt of the Earth on its axis. When a hemisphere tilts towards the sun, the sun is visible for more hours than when that same hemisphere is tilted away from the sun. This difference in winter and summer daylight hours increases the closer one gets to the poles.

In the northern hemisphere, the Arctic Circle marks the latitude (distance from the equator) where the sun does not dip below the horizon on the summer solstice (June 21) and does not rise above the horizon on the winter solstice (December 22).

The Global Warming 101 Expedition will begin south of the Arctic Circle on February 14 and will cross the Arctic Circle after leaving Pangnirtung. Look at the chart below to discover how much daylight the expedition team will have on different days. In Iglulik, our northernmost stop, the sun will rise at 2:03 a.m. on May 18 and will not set again until 1:08 a.m. on July 25.

The constant daylight in the summer and the constant darkness in the winter is a defining characteristic of life in the Arctic Circle (above 66°33’N). Global warming affects even the darkness of the Arctic winter. Inuit people notice that the darkness is not as dark as it once was. Wayne Davidson, a weather station operator, discovered that this is due to a warmer layer of air that reflects sunlight over the horizon (Source: Struck, D. Inuit see signs in Arctic thaw, Washington Post, March 22, 2006.)