The Leidenfrost Effect
Why water droplets dance on hot pans
You've probably dropped water on a hot pan before. At moderately hot temperatures it sizzles and evaporates instantly, but when it's really hot, the water droplet balls up and rolls around.
The Principle
When a water droplet hits a very hot surface (200Β°C+), the contact surface instantly vaporizes. This steam creates a thin gas layer beneath the droplet.
This steam cushion lifts the droplet off the surface. Since the droplet isn't directly touching the surface, heat transfer slows down and evaporation actually takes longer.
Counter-Intuitive
You'd think higher temperature means faster evaporation, but above a certain temperature (the Leidenfrost point), things reverse.
100Β°C: Water boils and evaporates quickly
150Β°C: Evaporates even faster (sizzle sound)
200Β°C+: Droplet floats and actually evaporates more slowly
Simple Experiment
Heat a pan on high for 2-3 minutes, wet your finger, and drop a single drop. You'll see the droplet ball up and glide around the pan surface.
How It Works
Water droplet contacts 200Β°C+ surface β contact area instantly vaporizes
Vaporized steam forms thin cushion beneath droplet
Steam cushion blocks heat transfer β droplet floats and evaporates slowly