Islande: Pluie et vent à GILSFJORDUR, route 590. - 4) THE NORTHERN LIGHTS: The brightest auroras are usually in the spring and automn rather than midwinter, but a release of particules from the sun can create fine displays at any time. The aurora often forms arcs across the sky in a direction from south west to north west, at right angles, to a compass needle. Sometimes long rays are seen, converging towards a point near the zenith. This phenomenon is known as the "corona".