The global near-surface temperature increased by ~0.155 K per decade during 1979–2012, which resulted in decreasing snow and increasing rain events, retreating mountain glaciers and more frequent and intense rainfall extremes. Although surface temperature increases are well studied, less attention is given to the associated changes in the tropospheric thermal structure, such as melting level height, which affects cloud microphysics and surface precipitation. Here we use observations and reanalyses to show that the melting level height increased by 32 ± 14 m per decade over global land areas during 1979–2010, consistent with a warming atmosphere. This causes a transition from snow to rain, the enhanced melting of hail and an increased depth of warm cloud layers (cloud base to melting level distance). Warm cloud layers with a depth beyond ~3.5 km result in an intensification of extreme precipitation at twice the rate of the atmospheric moisture increases. Days with such environments increased by 25% per decade in populated regions, such as the eastern United States.

1979-2012年期间，全球近地表温度每十年增加〜0.155 K，这导致降雪和降雨事件增加，山间冰川撤退，极端降雨频繁和强烈。尽管对表面温度升高进行了很好的研究，但对流层热结构的相关变化（如融化高度）的关注较少，这会影响云的微观物理学和表面降水。在这里，我们使用观察和重新分析表明，在1979-2010年期间，全球陆地区域的熔融高度每十年增加了32±14 m，这与大气变暖是一致的。这导致了从雪到雨的过渡，冰雹融化的增强以及暖云层深度的增加（云层到融化高度的距离）。温暖的云层深度超过〜3。5 km导致极端降水的加剧，速度是大气湿度增加速度的两倍。在美国东部等人口稠密的地区，具有这种环境的日子每十年增加25％。