Rime, also known as "snow willow," "tree hanging" and "ice flower," is a kind of phenomenon where winter fog condenses on tree branches and leaves to form individual white ice crystals, according to meteorologists. Together with the Mountains and Water of Guilin, Stone Forest of Yunnan and Three Gorges of the Yangtze River, Jilin Rime is regarded as one of the Four Natural Wonders of China. Since 1991, Jilin City has been holding the Ice and Snow Festival of Rime annually.

Freezing temperatures and warm water in Jilin contribute to the unique phenomenon. Jilin, which is located in Northeast China, is known for its cold winters where it falls to 20-25 degrees centigrade  below zero on the coldest days. The Songhua Lake beyond the Fengman Power Station is an artificial lake where the ice freezes over a meter thick. The water beneath the ice, however, flows quickly due to the power station turbines that help raise the water temperature to 4degrees centigrade. While the outside temperature is -25 degrees centigrade, the water, some 50 kilometers below the dam, flows freely. This process produces fog during the day, but when the temperature drops below zero at night, rime and icicles form on trees around the lake. When the sun rises the next morning, willow branches become silver bands and pine trees turn into white chrysanthemums. The white frost is best seen from the dam and along the shore. Water vapor rises up over the river's surface forming microcrystalline grains on tree branches near riverbanks and beautiful rime with a loose structure and pure white color. This is not possible in any other place in China except Jilin.

According to weather station records, Jinlin Rime usually appears from late November to early March. There are 23.5 days on average with the rime phenomenon in winter, and it is most frequently seen in January, over an average of 9.4 days. Rime is mostly formed after 1:00 am and grows promptly in the latter half of the night. It usually disappears when the sun is up high at noon with a stronger wind. The rime phenomenon lasts for an average 9.6 hours, with a record of 44 hours and 57 minutes.