The fraction of ice-containing clouds in eastern Eurasia was higher than in western Eurasia and globe with a peak difference of about 30% around -15 degrees Celsius. The fraction of ice cloud layers between −20 and −5 degrees Celsius was about 20% higher in eastern Eurasia than in western Eurasia. In this temperature range, ice particles are formed by the contact freezing and immersion freezing processes, and our results indicate that these formation processes were promoted in eastern Eurasia.
The fractions of ice and water cloud layers in the lower troposphere (below 3 km) were significantly distinct between eastern and western parts of Eurasia. The fraction of ice cloud layers below 3 km was higher in eastern Eurasia than in western Eurasia. This suggests that the formation of ice particles in eastern Eurasia is initiated at a lower altitude, closer to the ground surface, than in western Eurasia. We also considered that the impact of the ground surface on ice particle nuclei was larger in eastern Eurasia than in western Eurasia. The supersaturation and dynamics are important factors for ice particle formation and the subsequent evolution of the ice phase in the cloud layer.