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The Second Substorm

The Second Substorm

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A bitter wind blew across the icy mountainside in Björkliden, Sweden, while the moon illuminated the landscape below. I had heard about this overlook, but couldn’t find it in time to capture the first wave of auroras at 10PM. But since it was my last clear night in the Arctic, I waited until 1AM for the aurora to come back. A green stripe first appeared to the east, featureless and unmoving but slowly getting brighter. It was almost like a rubber band building up tension, until suddenly it released. Within seconds the northern lights filled the entire sky, moving and changing faster than I could possibly capture it. This is known as a substorm, and they occur several times a night when geomagnetic conditions are favorable. The solar wind piles up charged particles on the tail side of the magnetosphere. When the magnetic field line snaps, these particles are quickly funneled towards the Earth’s poles which causes a sudden expansion and brightening of the aurora. It’s not completely understood what triggers this ‘snap’. But the unpredictability is what makes the aurora so fascinating to watch, you never know what it's going to do next.

Copyright
Kevin Palmer
Image Size
6016x4016 / 14.0MB
Keywords
A bitter wind blew across the icy mountainside in Björkliden, Sweden, while the moon illuminated the landscape below. I had heard about this overlook, but couldn’t find it in time to capture the first wave of auroras at 10PM. But since it was my last clear night in the Arctic, I waited until 1AM for the aurora to come back. A green stripe first appeared to the east, featureless and unmoving but slowly getting brighter. It was almost like a rubber band building up tension, until suddenly it released. Within seconds the northern lights filled the entire sky, moving and changing faster than I could possibly capture it. This is known as a substorm, and they occur several times a night when geomagnetic conditions are favorable. The solar wind piles up charged particles on the tail side of the magnetosphere. When the magnetic field line snaps, these particles are quickly funneled towards the Earth’s poles which causes a sudden expansion and brightening of the aurora. It’s not completely understood what triggers this ‘snap’. But the unpredictability is what makes the aurora so fascinating to watch, you never know what it's going to do next.