This isn't exactly a source for a correct description of the tides, but it
could be an interesting contribution to a class discussion...
The tides thread got me to go look carefully at one of those calendars that
shows the predicted tides for the coming year. If you haven't seen these,
they look like a normal calendar, but with the local water height plotted
against time. They are available for many different locations; if anyone
is interested, I can post the information on how to get them.
Anyhow, the calendar for the San Diego area shows approximately 2 high
tides per day, as expected. However, on closer inspection, the time of the
high tides *does not* coincide with when the moon is at zenith. In fact, I
found 2 days for which the tides were almost identical, one on a new moon
and one on a full moon!
--
--James McLean
jmclean@chem.ucsd.edu
post doc
UCSD