Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Sun Fei)

Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Jigme Dorje)

Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)

Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)

Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Purbu Zhaxi)

Photo taken on May 1, 2020 shows a solar halo over the base camp of Mount Qomolangma in southwest China's Tibet Autonomous Region. (Xinhua/Sun Fei)