Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Ice appears blue when the red (long wavelengths) part of white light is absorbed by ice, and the blue (short wavelengths) light is transmitted and scattered.

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)

Chunks of blue ice pile up on Qinghai Lake, China's largest inland saltwater lake in Hainan Tibetan Autonomous Prefecture, northwest China's Qinghai Province, Feb. 13, 2025. (China News Service/Xue Di)