adarcy
New member
Tides - you\'re all wrong
Sorry to all for not appending to the previous thread on tides, but I've been away and catching up and it's scrolled off the first page.
Here goes, davel asked the most pertinent question i.e. how can Portsmouth and the Scilles be 6 hours out of phase if it's all to do with the moon and the sun?
I ask what about amphidronic points? Do a google but they are points on the globe where there is NO tidal range. The further away from them the higher the tides are. I am no expert but I am told they have been identified in the middle of oceans and one is calculated to be somewhere in the New Forest (if it had any water to show it).
To clear what IMHO is misinformed speculation, I don't think clouds are going to effect the gravitational attraction of the moon or sun on the water below and one must allow for the effect of land and sea bed shape and height on the expected tidal height but .... a simple push-and-pull on the water explanation cannot be right if there are areas where the water height does not go up and down!
Simple explanations are good enough for most people and may work well enough for most uses but still may not be right.. The more you look into it the less we seem to know about tides. For x hundred years the Admiralty has refined its tidal estimations for ports on an increasing number of correction factors obviously most put down to local observations and then correcting saying it is due to local geographic factors. But, to the best of my knowledge, no one can explain amphidronic points satisfactorily. Does this remind you of endless "perfect" cycles explaining the sun going round the earth until ?Copernicus solved it with a much simpler and accurate explanation of the earth going round the sun?
Please flame away or inform, not that it makes much difference as, like others, the tidal heights and streams always seem wrong for what I want to do and whether anyone understands them or not, I confidently expect them to continue to do so.
Anthony
Sorry to all for not appending to the previous thread on tides, but I've been away and catching up and it's scrolled off the first page.
Here goes, davel asked the most pertinent question i.e. how can Portsmouth and the Scilles be 6 hours out of phase if it's all to do with the moon and the sun?
I ask what about amphidronic points? Do a google but they are points on the globe where there is NO tidal range. The further away from them the higher the tides are. I am no expert but I am told they have been identified in the middle of oceans and one is calculated to be somewhere in the New Forest (if it had any water to show it).
To clear what IMHO is misinformed speculation, I don't think clouds are going to effect the gravitational attraction of the moon or sun on the water below and one must allow for the effect of land and sea bed shape and height on the expected tidal height but .... a simple push-and-pull on the water explanation cannot be right if there are areas where the water height does not go up and down!
Simple explanations are good enough for most people and may work well enough for most uses but still may not be right.. The more you look into it the less we seem to know about tides. For x hundred years the Admiralty has refined its tidal estimations for ports on an increasing number of correction factors obviously most put down to local observations and then correcting saying it is due to local geographic factors. But, to the best of my knowledge, no one can explain amphidronic points satisfactorily. Does this remind you of endless "perfect" cycles explaining the sun going round the earth until ?Copernicus solved it with a much simpler and accurate explanation of the earth going round the sun?
Please flame away or inform, not that it makes much difference as, like others, the tidal heights and streams always seem wrong for what I want to do and whether anyone understands them or not, I confidently expect them to continue to do so.
Anthony
