The slipperiness of ice when touched with our hands is due to a thin layer of liquid water that forms on the ice's surface. This phenomenon is known as "surface melting" or "regelation."
Ice has a melting point of 0 degrees Celsius (32 degrees Fahrenheit). When you touch the surface of ice with your warm hands, the heat from your skin is transferred to the ice, causing a localized temperature increase at the contact point. This increase in temperature melts a thin layer of ice, creating a thin film of liquid water on the ice's surface.
The liquid water layer acts as a lubricant, reducing the friction between the ice and your hand. This reduction in friction is what makes the ice feel slippery. It's similar to the way a thin layer of water on a surface can make it slippery, like a wet floor.
The process of surface melting and slipperiness is why ice skaters can glide smoothly across the ice. The pressure exerted by the blades of the ice skates lowers the ice's melting point at the contact point, causing surface melting and creating a thin layer of liquid water that allows for easy movement.
It's worth noting that the slipperiness of ice can be a safety concern, especially on walkways and roads. When the temperature is near the freezing point, ice can form a thin layer of water on its surface due to factors like sunlight or pressure from foot traffic, making it extremely slippery and hazardous to walk or drive on.