wind convergence - divergence

Good try Knightmare, but not sure we've really nailed the mechanism because: 

The wind approaching the lake (lets stay away from the sea to keep it simple)  and the wind on the landward side of either shore must be travelling at the same speed. The only thing changing as far as I can see is the wind over water which accelerates as it moves onto the water due to the lower friction. So isn't the Coriolus effect working on the faster wind on the lake  and if so why does the left shore wind turn and cross the lake edge to give the convergence? 

Hang in there.....

Obviously i meant a lift on port as you sail away from the bank. this lift will dissappear as you sail back into the air flowing over the lake. 

To my mind this means, and i may be out in a limb here, but as you sail into the left hand bank you will be knocked until you tack where you will be on a lift that dissapears as you sail away from the bank, and you will have better pressure.  On the right hand bank you'll be lifted as you sail into the bank but the pressure will decrease. when you have to eventually tack you will slowly be lifted as you sail back into the lake.

I stand ready to be corrected!

Originally posted by IanP The wind approaching the lake (lets stay away from the sea to keep it simple)  and the wind on the landward side of either shore must be travelling at the same speed. The only thing changing as far as I can see is the wind over water which accelerates as it moves onto the water due to the lower friction.

Not quite the wind over the water is actualy closer to the speed and direction of the high level winds so it is the wind flowing over the land that is changed more.

But basicaly the wind as it changes speed has to change its direction to keep the same amount of angular momentum. It is not a sudden change as with all things wind orientated the canges happen over a distance - there will be a gradual change in wind speed away/towards the bank and this will mean a gradual change in direction but the over all effeect is a convergence on one shore and a divergence on another.

 

I think it is quite confusing to think about the wind coming directly off of one bank as this does mean there isnt any convergence because all of the wind is shifted in the same direction. The effect is most noticable on a river with the wind flowing almost down the river so you have convergence one side and divergence the other.

The divergence is caused by the angle of the wind on the shore and the angle of the wind on the lake being different and heading towards one another.

Edited by KnightMare

Iv given up on trying to tell you which direction it turns to because it is the opposite direction depending on whether you are behind the wind or infront or it.  But my (very rough) diagram does have convergence ont he left as you go up wind

That looks exactly like the scrawl that is covering my desk where real work should be.  It could be we are all agreeing for the first time in forum history