The Baltic Sea’s Unusual Waves

The waves in the Baltic are unusual because the Baltic is a shallow sea, as shown in the following diagram. 

First of all it’s important to realise that waves are not just something which take place on the surface of the sea, but are also eddies that extend perhaps up to four or five times the height of the wave downward under the surface.

The above chart shows the wave height in November. Waves over 3 feet can be seen in the middle and at the end of the month. Each day the waves are a different height. Some of the waves are very tall, because the Baltic is a shallow sea.

Let’s have a look to see what happens to waves in shallow water.

 

If we look at the diagram which shows how wave motion is influenced by water depth, we can see in figure 1 how circular motion extends many meters under the surface, This circular effect decreases with depth, but even many wave heights under the surface is still quite prominent.

Figure 2 shows what happens to a wave approaching shallow water. When the circular motion makes contact with the seabed, the circles at the bottom get compressed, putting pressure on the circular motion above. This pushes up the waves making them taller.