Randy- Until Chris mentioned it I had forgotten about Inge Lehmann, who =
I once met at UCBerkeley when she was visiting Prof Perry Byerly.
See http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/p_l=
ehmann.html



                  Jim O'Donnell     =

        Geological/Geophysical Consultant
           GEOTECHNICAL APPLICATIONS
702.293.5664    geophysics@..........
702.281.9081 cell   jimo17@........

-- "Randy"  wrote:

The 1 NM per minute of latitude conversion is where I started as that is=
 what we used when I was flying.  I see the shadow zone has a range of d=
efinitions from 102 to 105 as beginning and 140 to 142 as ending dependi=
ng on the reference.  Is there a most accepted range or is it somewhat d=
ependent on location?  Is it a sharp cutoff or a gradual reduction over =
Randy- Until Chris mentioned it I had forgotten about Inge Lehm=
ann, who I once met at UCBerkeley when she was visiting Prof Perry Byerl=
y.
See http://www.amnh.org/education/resources/rfl/w=
eb/essaybooks/earth/p_lehmann.html



         &nb=
sp;        Jim O'Donnell  &=
nbsp;  
        Geo=
logical/Geophysical Consultant
      &n=
bsp;    GEOTECHNICAL APPLICATIONS
702.293.5664 &n=
bsp;  geophysics@..........
702.281.9081 cell   j=
imo17@........

-- "Randy" <rpratt@.............> wrote:
=

The 1 NM per minute of latitude convers=
ion is where I started as that is what we used when I was flying.  =
I see the shadow zone has a range of definitions from 102 to 105 as begi=
nning and 140 to 142 as ending depending on the reference.  Is ther=
e a most accepted range or is it somewhat dependent on location?  I=
s it a sharp cutoff or a gradual reduction over a few degrees?
 
Randy