Hi people, 1st post here, but have been lurking on and off for about a year.
I'm not sure if this is the right NG to post my question, but it does
seem weather related. well sort of, and it's one of those things I lie awake
at night thinking about:-)

The way I understand it, is tides are caused by the gravitation pull
from the moon and the sun. Looking at high/low tides of the Atlantic, it
seems the north east coast of the US has low tides as the same time as the
low tides on the west coast of UK. The water must be displaced somewhere and
I presume it is pulled up into a 'hump' by the moon passing over the
Atlantic.
I am no mathematician, but for tides to go in and out, the moon must
be displacing million and millions of tonnes of water.
Why then does the gravitation pull on the moon have no effect when it
passes over land?
Not a leaf on a tree or a flower will sway towards the moon.

Thanks for any help.

spuriousin wonder

"spurious" wrote in message
...


Hi people, 1st post here, but have been lurking on and off for about a year.
I'm not sure if this is the right NG to post my question, but it does
seem weather related. well sort of, and it's one of those things I lie awake
at night thinking about:-)

The way I understand it, is tides are caused by the gravitation pull
from the moon and the sun. Looking at high/low tides of the Atlantic, it
seems the north east coast of the US has low tides as the same time as the
low tides on the west coast of UK. The water must be displaced somewhere and
I presume it is pulled up into a 'hump' by the moon passing over the
Atlantic.
I am no mathematician, but for tides to go in and out, the moon must
be displacing million and millions of tonnes of water.
Why then does the gravitation pull on the moon have no effect when it
passes over land?
Not a leaf on a tree or a flower will sway towards the moon.


Well they probably *do* but you would never notice it what with the
effect of wind and all that. Do you feel lighter at certain times of the
day due to the moon's gravitational pull on you? Probably not
With the oceans it's a different thing of course. Water is mobile
and can be pushed around by gravitational forces far more easily than
solids can. And don't forget that proper tides only occur on oceans
that are several thousands of miles wide. That's one *big* body of water!
And even then you only get at most a few 10's of feet difference between
high tide and low tide. That's insignificant compared to the size of the
body of water we are dealing with.

Col
--
Bolton, Lancashire.
160m asl.
http://www.reddwarfer.btinternet.co.uk
http://www.reddwarfer.btinternet.co....rPictures.html

The moon's tidal pull is due to the difference between its gravitational
force on the centre of the earth and that on its surface, and is about one
ten-millionth of the force of gravity on the earth's surface. The earth's
surface therefore ought to be displaced by about that fraction of the radius of
the earth, i.e. about 60 cm. The fact that the tides are much higher than this
is due to resonance effects and the shape of ocean basins and bays etc.
The reason there are no tides on land is simply because the land doesn't
"give" in the same way that a large body of water does, at least in time
available (a few hours). The tidal force is far too small to have any
perceptible effect on individual objects (leaves, flowers, even Jumbo Jets).

Tudor Hughes, Warlingham, Surrey.

snip


Thanks for the replies Col and Tudor, but I still have problems getting my
head around this.
The moon will displace millions of tonnes of water, yet won't make my
hair stand on end as it passes over.

Sorry to be a pain, but in layman's terms please.

spurious no sleep for me tonight

spurious wrote in message ...


snip


Thanks for the replies Col and Tudor, but I still have problems getting my
head around this.
The moon will displace millions of tonnes of water, yet won't make my
hair stand on end as it passes over.

Sorry to be a pain, but in layman's terms please.

spurious no sleep for me tonight



Force = mass x acceleration (Newton's law)

The acceleration caused by the moon's gravitational pull is the same for your
head and the Atlantic ocean, yet the masses are very very different. So the
*force* on the Atlantic is billions of times greater than it is on your head !
And since nothing moves without a force being applied, your hair stays put but
the *whole of the Atlantic* ocean moves.

Sleep well :-)

Will.
--

" A cup is most useful when empty "
-------------------------------------------------------------------------------
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In uk.sci.weather on Sun, 3 Oct 2004 at 13:03:06, spurious wrote :

I am no mathematician, but for tides to go in and out, the moon must
be displacing million and millions of tonnes of water.
Why then does the gravitation pull on the moon have no effect when it
passes over land?

It does, but since the land is far heavier it doesn't move noticeably.

Another effect the moon's gravity has, is that of slowing the Earth's
rotation over geological time periods.

Basically, the drag of the tides has the same effect on the Earth as
putting your finger on a spinning top, i.e. slowing the spin. The same
effect also causes the moon to move further from the Earth.

At the time of the asteroid impact when the dinosaurs were wiped out,
days were about 20-21 minutes shorter, and there were about 370 days in
the year.

I dare say someone else could give a more technical explanation though.
--
Paul Hyett, Cheltenham

snip

Force = mass x acceleration (Newton's law)

The acceleration caused by the moon's gravitational pull is the same for
your
head and the Atlantic ocean, yet the masses are very very different. So
the
*force* on the Atlantic is billions of times greater than it is on your
head !
And since nothing moves without a force being applied, your hair stays put
but
the *whole of the Atlantic* ocean moves.

Sleep well :-)

Will.
--

Thank you Will, I understand what you are saying and feel a little foolish
in posting the question, still I bet others have read this thread and
wondered "yea why?"

thx

spuriousgood nites sleep tonite

"Will" wrote in message


Force = mass x acceleration (Newton's law)

The acceleration caused by the moon's gravitational pull is the same for your
head and the Atlantic ocean, yet the masses are very very different. So the
*force* on the Atlantic is billions of times greater than it is on your head !
And since nothing moves without a force being applied, your hair stays put but
the *whole of the Atlantic* ocean moves.

While in a "perfect environment" the simple answer works; placing two 5
ton pallets together on a concrete floor will not cause them to approach
each other. Nor will a piece of driftwood follow the sun or moon. If
that could happen, mountains would fall apart or move much more than
oceans.

It is the differences in the astrometry of (for example) the "three body
problem" that can not be overcome immediately by gravity : acceleration
that causes phenomena such as tides (for one.) The net sum of the
differences can and must be catered for every so often when there is
enough strain on the system. The inertia of the moon and earth being so
vast that this could take days or even weeks if......

Gets of soap box.

The explanation of the moon's effect on things has been over simplified
and this can be seen when comparing the rate of change of tides with the
rate of change of lunar position.

As it happens the moon's effect on the weather can easily bee seen if
you compare the times of the phases with the weather in the UK over a
few years.

Take a look at the run of events here for 1980 from March to May to see
what long term effect this can have:

http://aa.usno.navy.mil/data/docs/MoonPhase.html#y2004


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"Michael Mcneil" wrote in message
news:323ffc1329c466b5d5ba33b94a7b8b42.45219@mygate .mailgate.org...
"Will" wrote in message


snip

While in a "perfect environment" the simple answer works; placing two 5
ton pallets together on a concrete floor will not cause them to approach
each other. Nor will a piece of driftwood follow the sun or moon. If
that could happen, mountains would fall apart or move much more than
oceans.

It is the differences in the astrometry of (for example) the "three body
problem" that can not be overcome immediately by gravity : acceleration
that causes phenomena such as tides (for one.) The net sum of the
differences can and must be catered for every so often when there is
enough strain on the system. The inertia of the moon and earth being so
vast that this could take days or even weeks if......

Gets of soap box.

The explanation of the moon's effect on things has been over simplified
and this can be seen when comparing the rate of change of tides with the
rate of change of lunar position.

As it happens the moon's effect on the weather can easily bee seen if
you compare the times of the phases with the weather in the UK over a
few years.

Take a look at the run of events here for 1980 from March to May to see
what long term effect this can have:

http://aa.usno.navy.mil/data/docs/MoonPhase.html#y2004


Just as you get me really interested in your theory, the bloody link don't
work.-)

spurious

"spurious" wrote in message


Take a look at the run of events here for 1980 from March to May to see
what long term effect this can have:
http://aa.usno.navy.mil/data/docs/MoonPhase.html#y2004

Just as you get me really interested in your theory, the bloody link don't
work.-)

1 Feb 02:21
9 Feb 07:35
16 Feb 08:51
23 Feb 00:14
1 Mar 21:00
9 Mar 23:49
16 Mar 18:56
23 Mar 12:31
31 Mar 15:14
8 Apr 12:06
15 Apr 03:46
22 Apr 02:59
30 Apr 07:35
7 May 20:51
14 May 12:00
21 May 19:16
28 May 21:28

Which translates to:

2 Jan 09:02 Thundery

10 Jan 11:50 Windy and overcast

17 Jan 21:19 Humid and breezy

24 Jan 13:58 Fine

1 Feb 02:21 Unsettled with a spell half way between ho hum to thundery.

9 Feb 07:35 Unsettled with a spell half way between wet to fine. Usually
bloody awful or there is trouble brewing.

16 Feb 08:51 Breezy & humid.

23 Feb 00:14 Windy and overcast

1 Mar 21:00 Here we go then. Thundery.

9 Mar 23:49 Similar to 23rd Feb, nothing to write home about.

16 Mar 18:56 Wet.

23 Mar 12:31 Unsettled with a spell half way between dull and overcast,
with a tendency to mist or light drizzle and wet.

I think the type of thing this produces is of the Levant variety. Those
readers with records of their own* may dismiss this as a load of tosh
but when things don't occur as the code predicts then the system starts
to overload.

31 Mar 15:14 Humid and breezy. (These humid and breezy ones count as
thundery weather world wide by the way. And unsetled spells to boot.)

8 Apr 12:06 Cassic: dull and overcast, with a tendency to mist or light
drizzle

15 Apr 03 46 Unsettled with wind and rain.

22 Apr 02 59 Thundery.

30 Apr 07:35 & 9 Feb 07:35 Unsettled with a spell half way between wet
to
fine. Usually bloody awful or there is trouble brewing.

7 May 20:51 & 1 Mar 21:00 Here we go then. Thundery.

14 May 12:00 & 8 Apr 12:06 Cassic: dull and overcast, with a tendency to
mist or light drizzle

21 May 19:16 Interesting repetition.

So now you know what to look for.


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