Northern Lights (Aurora Borealis)

The northern lights are solar particles that are thrown out into space from the storms at the sun's surface. The particles are drawn here by the earth's gravity, and the magnetic North Pole. Northern Lights particles hit the atmosphere in a ring-shaped zone around the pole. When the particles hit the atmosphere a chemical process similar to that happens inside a fluorescent light starts, energy is released and forms the light.

Tromsø is located right in the auroral zone, and is therefore among the best places to observe this phenomenon. Northern Lights outbreaks in Tromsø seem mostly like green light clouds, but some outbreaks may also provide other colors.

The best time to see the northern lights is when it is dark and clear weather, from September through April. The northern lights occur most of the time between six o'clock in the evening and two at night. Some people like to see the show from a mountain far from city lights, while others may be lucky to see it from the center of Tromsø.

Here you can see the aurora activity in the atmosphere, the metering station is on Kilpis in Finland.

Here is another page that aurora-related.

Northern lights forecast from The Geophysical Institute

Northern lights forecast from TV2