Sea water properties

Dr Mirjam Glessmer, currently working at the Geophysical Institute, University of Bergen, invited me to watch her demonstrating the interaction of sea water and fresh water when subjected to centrifugal forces. 
So... we have salt water dyed magenta held in an upside down flask in the centre of a tank filled with fresh tap water. 
The circular tank revolves and the flask is removed....the denser salt water, held by the fresh water, and due to the centrifugal forces, initially looks a bit like a fried egg with a darker central yolk, and with two additional small outlying eddies.....
a column with a sloping front develop in the rotating system, and begins to form a dome,

When the revolving tank is stopped magenta-dyed salt water billows out evenly across the tank, slowly mixing with the freshwater.
Density of seawater is higher than fresh water. Viscosity (i.e., internal resistance to flow) of seawater is also higher than that of fresh water. 
Thank you Mirjam!
(Dr Mirjam Gleßmer is a Postdoctoral Fellow in Physical Oceanography/‪Climate Dynamics‬ at the Geophysical Institute, University of Bergen).

Staying at Ann Karin's house, overlooking the sea at the entrance to Bergen between the Askøy and Sotra suspension bridges, I spent a lot of time watching the sea traffic - small speed boats, sail boats, vast cruise ships, tug boats, containers and reefers, even the occasional rowboat - passing by, and the ever-changing surface of the sea flowing back and forth, waves and ripples spreading out from the boats. But even when vessels were not passing there were times when we could see areas where the surface of the water was disturbed - a sort of agitated flurry on the surface, and flow lines  - and these were probably caused by fresh water flowing off the land into the sea and the interaction between them.

Magenta seas


  1. AnonymousJuly 08, 2012

    After looking again for your paintings at your web-site I tried to search for more information about “sticks and shells” – and found some analogies from other sea-people:
    “Marshall Islands Sailing Charts” -

    “Marshall Islands stick chart“ -

    “The charts represented major ocean swell patterns and the ways the islands disrupted those patterns, typically determined by sensing disruptions in ocean swells by islands during sea navigation. Stick charts were typically made from the midribs of coconut fronds tied together to form an open framework. Island locations were represented by shells tied to the framework, or by the lashed junction of two or more sticks. The threads represented prevailing ocean surface wave-crests and directions they took as they approached islands and met other similar wave-crests formed by the ebb and flow of breakers.”
    Lit.: J. Genz, J. Aucan, M. Merrifeld, B. Finney, K. Joel, and Alson Kelen, "Wave Navigation in the Marshall Islands," Oceanography, Vol. 22, No. 2., pp. 234-245, 2009.

    Mirjam Glessmer

  2. Hi Janette, I was just made aware of the above comment. While it is nice and helpful, it certainly wasn't written by me, and I am a bit worried that someone chose to sign with my name. Mirjam

    1. Hi Mirjam
      Well not sure what has happened here... maybe they meant to refer to you... and not to sign it as you...
      I can try to see if I can remove your name...


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