Jim Green says,"It is not true that the earth's oceans can rapidly respond to t
he forces acting on them." While I do agree with much that Jim says about
tides I can not agree with this statement. The rate of response is strictly
a function of rheology and is independent of all the other complexity of
tidal response. Simple rheological models can very accurately model the
response of water and by any reasonable use of the word rapid the response
is rapid.
I think it would be more accurate to suggest that the response might be
unexpected and that many of the simple tidal models are quite inaccurate and
misleading because they consider only forces due to gravitational gradients and
ignore many other factors which may in time be responsible for the dominant
tidal effects. Can you buy this Jim?
At the same time I hope Jim will also grant that it is after all these
gravitational gradients that are responsible for all that water sloshing around
These gradients must initiate the tides and must supply the energy that keeps
them going in spite of all the viscous damping. Furthermore, I submit that
there is very good evidence for the slowing of the earth's rotation and that
this strongly supports the contention that on the average the tides must
lead the moon.
At the same time I will grant to Jim that even when one recognizes viscous
damping,resonances, etc. the actual results of all these factors interacting
are indead surprising to me and the relationship between tides and
gravitational gradients is certainly obscure and not at all like what one
would imagine from reading standard textbooks. Thus, I have learned that
when planning a sea kayaking trip I take my tidal charts, and leave my text
books at home. It's hard to go wrong with empirical data!