snowline
/ˈsnəʊlaɪn/noun
(常作the snowline)
1- the altitude above which some snow remains on the ground in a particular place throughout the year万年雪线（高山上有常年不融雪的最低界线）。
1.1
- the altitude above which there is snow on the ground in a particular place at a given time雪线（在特定时间特定地点高山上有雪的最低界线）。