Tasiilaq is the largest city at the east coast of Greenland.
The light at the top of the mast is a warning light. When it flashes a piteraq is eminent and people are advised to take cover as soon as possible.
Piteraq means "that which attacks you" and is a cold katabatic wind from the Greenland icecap. It can reach windspeeds of more than 80ms / 290km/h / 180m/h.