科学素养与生活应用·英语30篇（2）

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北极熊毛发透明却显白色的原因

Polar bear fur looks white, but each hair shaft is actually hollow and completely transparent.
Sunlight enters the clear hairs and scatters in all directions due to internal reflections.
This scattering effect makes the fur appear bright white under most lighting conditions.
Beneath the fur, their skin is black to absorb heat efficiently from sunlight.
The hollow structure also traps air, giving excellent insulation against Arctic cold.
Scientists studied this using electron microscopes to map light pathways inside single hairs.
Unlike snow, which reflects all wavelengths equally, polar bear fur diffuses light selectively.
UV light passes through easily, helping vitamin D synthesis even in low-light winters.
Conservationists monitor fur condition as an indicator of health and pollution exposure.
Understanding this natural optics inspires new designs for solar-reflective building materials.