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University of Bergen
Geophysical Institute

24 days of kitchen oceanography

Each day a new experiement will be posted here. Reveal what is hidden behind the windows by clicking on the arrows below.

Introduction
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
Day 11
Day 12
Day 13
Day 14
Day 15
Day 16
Day 17
Day 18
Day 19
Day 20
Day 21
Day 22
Day 23
Day 24

Main content

Oceanic overturning circulation

Day 2
02.12.2020

Why does the red water flow on top and the blue water at the bottom?

Termohalin sirkulasjon
Photo:
Mirjam Glessmer, GFI

Experiment 2:

We take a rectangular container and fill it with lukewarm water. We then place a frozen cool pack over the edge on the right side. Now we drip blue food coloring on the cool pack, and drip warm red food coloring on the left edge. The blue color marks the water mass cooled by the cooling pack, the density of which increases as a result of the cooling and which therefore sinks to the bottom of the container. The red color marks the warm water on the surface. Due to the constant sinking of the cold water and its spreading along the bottom, warm water is pulled towards the cool pack and cools there until it starts sinking, too.

Chapter 2: Oceanic overturning circulation

But above the water surface there is air, the atmosphere. The temperature of water at the sea surface, as well as its salinity, is constantly changing because of exchanges with the atmosphere. The atmosphere can cool water down or heat it up. In some regions, for example in the Greenland Sea, water becomes so cold – and thus heavy – that it sinks, away from the surface. To replace it, water from other regions is pulled in.