The winter is reflective of the barren nature that takes a hold over Russia in the wake of revolutionary change.  The winter represents the sense of deadening of hope that grips Russia.  For Yuri, the winter represents a world in which beauty and poetic expression has gone.  The winter represents a setting in which there is an emptiness in life.  Yuri encounters the winter while he is estranged from both love and his art.  The snow and the coldness that accompanies it are both realities that Yuri encounters.  The winter represents the period in which hope has perished.  Consider the excitement about Russia entering the First World War as Spring, with the reality of Russian suffering in the war as the winter.  The zeal and passion about revolutionary change replaced by the bleakness of a world in which Lenin and Stalin have effectively crushed all spirits.  This is where the winter occupies such an important role as being a metaphor that goes far in expressing the human condition as one where the springtime hope is met with its countervailing force of winter bleakness.