On Thu, 19 Mar 2009 17:00:04 +0000, Big Wings wrote:

Further to earlier post. Gravity is measured in Gals (in honour of
Galileo), 1 Gal = an acceleration of 1 cm/sec2. Average gravity at the
surface is 980.654321 Gals (or so). At the poles it is more at about
983 Gals and on equatorial mountain tops only 977 Gals - a difference of
about 0.6%. There are significant local variations. Now if we start to
take height into account...

I notice that's not an SI unit. Is the Gal some sort of engineering or
specialist geological unit? Its a pretty big unit for gravimetry, since
the maximal variation at the earths surface is only 6 Gals.

The SI unit is uM/s^2 (micrometers per sec squared), or 0.1 milliGals,
which looks more in tune with what satellites and aerial surveys are
measuring these days.

By the way, what happened to the discussion about slow tows?

Got too slow and stalled in.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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