eyjafjallajökull * volcano

A slowly spreading plume of volcanic ash from Iceland is covering parts of Europe, shutting down air travel and stranding tens of thousands of passengers around the world. The ash cloud forced Europe’s two busiest airports, Heathrow in London and Charles de Gaulle in Paris, to cancel all non-emergency flights Thursday.

“What we are seeing in Iceland is that as the magma particles get towards the surface, they interact with the very cold water and they chill to form glassy fragments and these glassy fragments are small, they have sharp edges and when those get up in the air that is what is causing the risk to aviation,” says Colin Macpherson, a professor of Earth sciences at Britain’s Durham University.