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Tidal Current Speed
When looking at graphs of tidal current speed, they describe the current changing in a way that seems counter-intuitive to me. They typically show a sine wave form with a horizontal line across line across the chart that denotes no current. Above the line is the current speed coming in (flooding), below going out (ebbing).
Interpreting this chart, I expect that at slack tide, when the curve crosses the center line, the water should be basically still, but a moment after that precise moment, it starts to accelerate very quickly to near maximum speed.
When I observe the tides, however, I see something different. It rises quickly, but as it approaches its azimuth, the rate of rise slows until it reaches the peak, at which time there is no movement for a while. Then the speed gradually starts to increase. For that to be charted, the rise would be less steep than what I see on the above chart.
Am I missing something? How does it really behave?
Last edited by jbondy; 07-11-2008 at 12:06 PM.
Reason: Inserting graph