Interstate 80 Westbound, 6:12 a.m. – Invisible Ice Apocalypse. It looked harmless at first: just another gray, slushy dawn with a few lazy snowflakes drifting down. Commuters had their wipers on intermittent, coffee in hand, radios low. Then the temperature plummeted two degrees in a minute and the road turned into a skating rink nobody could see.The first sign something was wrong was the red glow. A sudden tsunami of brake lights lit up the horizon and raced backward through traffic faster than