Cars sliding helplessly down an icy hill
While reporting today's article on the use of salt to de-ice roadways, I came across this video of cars sliding down an icy hill in Portland, Oregon. It appears the clip originally ran on KING4, the NBC news affiliate in Seattle.
I also found a Web site put together by Frostburg State University that offers a detailed explanation of why salt melts ice.
Essentially, the salt prevents water molecules from attaching to the ice surface. Simultaneously, water molecules continue to peel away from the solid ice surface, causing a net reduction in ice mass - or "melting," as we like to call it.
In addition to the graphic above, which shows water molecules coming and going from an icy surface, Frostburg's site offers a nice interactive Flash animation explaining how salt changes this process.
