This is three illustrations showing how a glacier is formed. In this and the following section we will look in detail on how a glacier flows and what is meant when we say that a glacier is in balance.
A glacier is formed when more snow falls during winter than melts away during summer. With every year that passes the snow drift will increase in size because new snow will fall on top of the snow from the previous winter.
When the glacier grows the snow will be compressed until it turns into ice. The ice will start flowing down the hill. At some point the snout of the glacier will have reached so far downhill that it is warm enough for the ice to begin melting more during summer.
The snout of the glacier will at some point reach so far downhill that the ice will melt as fast as it flows. If the climate does not change, the snout of the glacier will stay at the same spot melting away as quickly as new ice is transported down. When this happens the glacier will not change shape and you can say that it is in balance.