This is your “who knew” science class for the day.

It’s called the Leidenfrost effect, and you have probably already seen in your own kitchen, but I bet you have never seen it filmed close-up at 3,000 frames per second? Thanks to Nathan Myhrvold and his Modernist Cuisine team, now you can.

The Leidenfrost effect works of the theory that instead of boiling away instantly, if the skillet’s hot enough water is insulated by a thin layer of its own vapor, and gracefully skims across the pan.

If the temperature is hot enough in a dry pan, after dropping some H20 on it, you will see that the water drops will dance around the surface for some time before they disappear. But when it gets to 190 ºC or 374 °F, the droplets will not evaporate for quite a few seconds. In fact, Sir William Fairbairn—a famed Victorian steam boiler designer—found that, while a water droplet evaporated in a hiss at 334 °F, it survived for an amazing 152 seconds at 395 °F (202 °C).

Believe it or not, it’s the same principle that enables people to walk on hot coals. Your feet start out on a damp surface (typically wet grass), and a small amount of vapor insulates your feet and prevents them from burning. Of course, if you stand there for an extended period of time, the effect is negated, as the water would all evaporate.

[Cheers popsci.com]