Why is glacier ice blue?

Glacier ice is blue because of the refraction of light.

Glacier ice is not formed by liquid water, but by solid snow.

After the formation of glacier ice, the small bubbles inside will become smaller and smaller. When they are small enough, they scatter sunlight. In the sun, long-wavelength red light and orange light are not easy to be scattered, while short-wavelength blue light and purple light are easy to be scattered, so like the blue sky, glacier ice has become a pleasing blue.

Extended data:

The principle that glacier ice appears blue is the same as the sky, which is light scattering, except that tiny bubbles in the glacier ice replace gas molecules and water droplets in the atmosphere.

The water in the glacier is relatively pure, because the snow falling in ancient times has been continuously compressed for thousands of years, and the impurities originally contained in the snowflake are squeezed to the edge of the snowflake crystal and washed away one by one, taking away the finally formed ice, especially the ice formed by single crystal flowers, just like the water distilled for three times.

Baidu Encyclopedia-glacier ice