While summer in most of the world means wearing shorts and trips to the beach, in the Arctic, it means perpetual daylight.
On March 18, spring first began in the Arctic as the sun rose for the first time in six months. The sun gradually rose in the sky until on June 6, everywhere north of the Arctic Circle was bathed in sunlight 24 hours a day.
An image from NASA's Aqua satellite shows the western Canadian Arctic on June 10, 2010, a few days after perpetual sunlight commenced for the entire region.
June 21 is the day of the summer solstice, when the North Pole is pointing toward the sun as much as is possible because of the tilt of the Earth's axis. The sun will be as high in the sky as it can go at 7:28 a.m. EDT (11:45 UTC) and will stay in the sky for a fraction of a second longer than the day prior or the day after.
The NASA image of the sun-bathed Arctic captures the region in a moment of transformation; signs of winter are still present, but summer is clearly on the horizon.
Sea ice in the Beaufort Sea has started to break up. A swath of open water, black in the image, separates the land from the dense pack of sea ice. Ice still fringes much of the land, but it is thinning. In many places, particularly around Banks Island, the land-bound sea ice is blue, pointing to thin ice or the presence of water on the ice.
Spring is beginning to touch land as well. While frozen lakes punctuate the landscape with white, many lakes are clear. The Mackenzie River flows ice-free to a broad partially frozen delta. Trapped behind a dam of ice, the muddy brown waters blur across the triangular delta. The water that is getting through the ice carries sediment into the Beaufort Sea, coloring the waters near the shore brown and green.
With access to constant light, flowing water, and warmer temperatures, plants are beginning to grow. The land around the Mackenzie River has a deep green hue. The line between tundra and forest runs through this image. The forest is dark green, while the tundra is still brown.
The land also shows the first sign of summer: large forest fires. One large forest fire is outlined in red. Smoke from nearby fires flows across the lower left corner of the image. The boreal forest needs fire to maintain the ecosystem, and large fires happen regularly in the summer. In the remote region shown here, lightning ignites most forest fires.