Why is ice slippery?

Everybody knows you need to watch your step when it’s icy outside. But what makes ice so slippery?

Extra slippery water

If you walk or skate on ice, your feet or skates push down on the ice and scrape it. This causes a small part of the ice to melt, creating a very thin layer of liquid water – about one hundred times thinner than a hair! – on the surface of the ice.

This extremely thin layer is what makes the ice slippery. That’s because this water isn’t the same as the water that comes out the tap. It’s a thick mix of very cold water and bits of ice, like a slushy. That slushy water is much more slippery than tap water.

In some cases, a layer of water gas might form on the surface. This makes the ice slippery, but for a different reason. The gas particles roll over each other if you step or skate on them. It’s like walking on a layer of microscopic marbles!

Very complex

Ice is slippery because of the layer of slush or gas you create by moving on it. The slipperiness of the ice depends on what’s underneath you. And that depends on all sorts of factors: the shape of your shoes or skates, your weight, your speed, the temperature and so on.

It’svery complex. Researchers have been studying ice for years, yet they still don’t know exactly why it’s so slippery. What we know so far is only the tip of the iceberg!

Answered by Yannick Fritschy