Re: Moon causes tides, why is Mediteranian sea not tidal?

Hi Barrie:

The Mediterranean does indeed have tides, they are just quite small. Even large lakes have tides, though they too are generally very small.

There is actually quite a lot of water moving through the Straits of Gibraltar with every tide - Current speeds can be upward of 6 knots (about 11 km/hr). There are actually two flows, an outward (i.e. Atlantic-ward) deep flow of warm, salty water, and an inward (i.e. Mediterranean-ward) surface flow of fresher Atlantic water. The volume transports of those flows is something like 0.6 to 0.8 Sv (a Sv is an oceanographic unit to describe the movement of water masses called a Sverdrup, and 1 Sv is a transport of one million cubic metres per second). That's actually not a huge transport in the grand scheme of things (for instance the Gulf Stream transports something like 20 to 30 Sv), but is still a heck of a lot of water given how narrow the Strait is. The Atlantic-ward deep outflow, for instance, forms a characteristic layer that Oceanographers call Mediterranean Intermediate Water, and it extends out into the Atlantic for several hundred miles at a depth of around 1000 metres.

I hope that answers your question,
Rob Campbell, MAD Scientist