Hear the Otherworldly Sounds of Skating on Thin Ice | National Geographic

What characteristics make black ice ideal for Nordic skating?

• Its dark color and rough texture.

• Its extreme thickness and cloudy appearance.

• Its smoothness and ability to produce high-pitched sounds.

• Its rapid melting rate and uneven surface.

What is the minimum thickness black ice can be while still supporting the weight of a skater?

• 45 millimeters

• Two inches

• One foot

• Ten centimeters

How does thin black ice support the weight of a skater without breaking?

• The ice forms a dome or arch structure, distributing the weight to the sides.

• The ice is extremely dense, making it inherently strong.

• The skater's light weight prevents the ice from cracking.

• The ice is reinforced by air bubbles trapped within it.

What factors are important for ensuring safety when skating on thin ice?

• The skater's speed and agility.

• The color of the ice and the time of day.

• Temperature, atmospheric conditions, and careful advance planning.

• The presence of other skaters and loud noises.