Northern Lights in Montana (AP)
Montana was also treated to a stunning northern lights display, in October 2013. Photo by AP
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For visitors to northern Sweden's Abisko National Park, Christmas Day arrived with a bang on Wednesday, December 25, with a series of spectacular "northern light" shows.

The Aurora Borealis occurs when charged particles emitted by large solar flares collide with gases in Earth's atmosphere. With the sun approaching the midpoint of its natural, 10-13 year solar cycle, there have been more solar emissions than usual in recent months, and more spectacular light shows over the Arctic as a result.

By coincidence, the Christmas Day show over Lapland was spectacular.

The colors are dictated by the altitude and individual gases involved in the collisions. Green is the most common color and is produced by oxygen atoms at an altitude of about 240 km.

Red is rarer, involving oxygen at an altitude higher than 150 miles.

Blue and purple are produced by nitrogen atoms closer to earth at an altitude ofnearly 100 km.

Local tourism business owner and videographer Chad Blakley says he's taking full advantage.

"Yesterday afternoon we experienced a very merry Christmas in Abisko National Park. My wife and I were just settling in and beginning our Christmas celebrations around 3:00 PM when one of our guests informed me that a small aurora was developing above Abisko National Park," he said.. "I immediately grabbed my camera gear and sped down to one of my favorite places in the Park to photograph the northern lights - the frozen shore of Lake Torneträsk. I quickly set up my camera and by 3:30 PM the sky was full of red and green auroras - the perfect colors for Christmas."