根据现有的古地质研究结果发现，在大约6-7亿年前的新元古代时期，地球至少经历了两次历史上最为严重的全球性冰川期，研究者据此提出了“冰雪地球”假说。利用耦合大气模式数值模拟全冰封的“冰雪地球”和南北5度为开放洋面的“雪水交融的地球”两种极端气候状态，发现与现在地球经向三圈环流迥然不同的四圈环流结构，其中哈德雷环流的垂直尺度只有9km，其下沉支在南北20度的地方，中心强度是现在的4-7倍。这种较强的经向运动把较多的热量输送到副热带，使赤道附近的温度不易升高。

According to existing results of pale-geology, the earth had experienced at least two most several global glaciations in Earth’s history during the Neoproterozoic about 600-700 million years before. According this researchers proposed “Snowball Earth”hypothesis.Using Community Atmosphere Model Two, simulate two kinds of violate climate state of a globally ice-covered “Snowball Earth”and a “Slushball Earth”with open ocean between 5S and 5N.It is interesting to discover that four-cell atmospheric circulation exists on the “Snowball Earth”and “Slushball Earth”,which is mush different from the modern earth.The Hadley circulation is only nine kilometers high,between 20S and 20N，and its center power is 4-7 times greater than now. So great meridional motion takes more heat to the subtropics, and therefore the temperature of the tropics is hard to rise.