16th December: Frozen Shoreline
The cold weather has continued and looking out over the river on Friday 16th December the shoreline in front of Bitterne Manor Park was white. While most of the water in the river at high tide is salt water, the freshwater flowing down from Woodmill floats on top of the wedge of salt water below, even when the tide is coming in the surface flow is often towards Southampton Water. This is called “estuarine circulation“. As a result the surface water is cold, having come from the cold inland areas, and brackish from what ever turbulent mixing has taken place. On a cold night the shallow water at the edge of the river can start to freeze. What was surprising on this day was that the ice did not melt; I was busy in the morning but the ice was still there around 15:00 when I took the photos.
There was less ice on “my side” of the river on the 16th, more on the 17th…
…but my side of the river faces south and gets the sun, whereas the trees in Bitterne Manor Park shade the foreshore there.