THE NOT QUITE ALL-WEATHER MODE. Tunnels and caves hold their temperatures longer than the great outdoors, which has disrupted Eurostar operation through the Channel Tunnel.

The trains became stuck in the tunnel because the air inside was much warmer than the air outside the tunnel entrance in France, Eurostar spokeswoman Amelle Mouhaddib told CNN.

"It's a bit like taking a bottle of beer out of the fridge into a warm room -- within minutes it's covered in condensation," said Eurostar CEO Richard Brown.

He describes the event as "completely unprecedented." Not necessarily. An electric locomotive as dependable as the GG-1 was brought down by a particularly fine snow that got through the screens on its air intakes. Some of the motors were re-equipped with intakes higher up as a corrective.