Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    Re: CNAV and Rearranging the mass of the earth's water?
    From: Brad Morris
    Date: 2019 Jan 23, 12:19 -0500
    Hello Mark

    You asked: wouldn't all sea levels rise uniformly?

    If there wasn't an external perturbation of the system, then yes, they would.  Think of any pool of water, undisturbed.  But there are disturbances to the oceans.  There are the two large external gravity wells, the sun and moon.  Each provides a pull on the oceans, sometimes in the same direction but often in differing vectors.  The bulges of water remain oriented towards those vectors, with the earth rotating, creating the tides.  But we don't live on a perfect sphere of water, there are intervening land masses which channels the water and create flow.  There are plenty of other disturbances to the system to investigate.  In the end, however, the unequal water levels cannot be exaggerated to infinity.  The levels are primarily influenced by the earth's gravity well.

    Elsewhere, in your post, you asked of the effect of the redistribution of mass on the orientation of the earth, and would this change CN.

    In my opinion, the redistribution of the mass of ice in the polar caps would be the greatest change in distribution of mass.  The change in sea level would have a much lower effect.  So yes, there will be a change in orientation. Yet this orientation change can be readily accounted for, just like all of the other factors, such as precession.The method won't change, but the raw data input will.  A perfect example of this is a star with high proper motion.  While it isn't exactly streaking across the sky like a jet fighter, it is changing its orientation with respect to the other stars.  The daily pages of the NA account for this change.  Why then, I would ask, should a redistribution of the earth's mass have an effect we cannot account for?  No need to correct the instructive textbooks or methods.  Just update the raw data, which is something we have been doing all along.  The earth is not about to start tumbling in a random and chaotic way.  

    I don't think there is any need to panic about this with regards to CN.  

    Perhaps the effect on the ecosystem might be of greater concern.  Nature has a systematic method of correct for life forms which dramatically change their environment.  There are die offs, in which the offending population is greatly reduced in numbers.  The historical record is replete with instances, as well as reproducibility in scientific experiments.  That may be slightly more concerning.


    On Jan 23, 2019 11:17 AM, "Mark Coady" <NoReply_MarkCoady@fer3.com> wrote:

    Yesterday the Providence Journal had an article on climate change. Here I quote a specific section regarding sea level changes:

     “Because of changes in ocean currents, water temperatures and other factors, seas are rising faster in the Northeast than just about anywhere in the world. A recent study by the National Center for Atmospheric Research estimated that cities could experience more than double the global mean average for sea level rise over the next two decades.

    From 1930, Sea levels in Rhode Island increased by about an inch a decade, until about 40 years age when the rate started to accelerate. The state has seen six inches of sea level rise since then.

    The Rhode Island Coastal Resources Management Council has adopted projections by the national Oceanic and Atmospheric Administration to plan for up to 11.5 feet of sea level rise by the end of the century.“

    I am wary of newspaper science, as the forum of front page journalism does not always  lend itself to technical precision....and this one invaded my consciousness which started drooling out unchecked random thoughts:  

    It set me to thinking about global mass, CNAV concerns, regional pendulums, gravitational fields, and how sea levels could be predicted to rise at greatly different levels regionally. The simple minded part of me goes back to digging a large fish pond using a full hose from corner to corner to keep the sides level. My gut level, which is of course overly simplistic, says that if the mass of ocean water were already dispersed based on the mass and gravity of this third rock and our other gravitational impacts like moon and sun.....why would it unevenly change the height of sea level if you added more water? Isn’t ultimately all one connected big puddle that would relevel at the end...?  OK... so I have no idea what I am talking about.......... but wouldn’t it re-disperse uniformly based on existing gravity...? Of course we do have all that melting ice...what of that......that’s relocating a substantial once solid mass while changing it to a liquid state.....

    If the stated occurred, would we be correcting our relationship with a cosmos because our center of Mass was re-arranged and our.... oh heck..... “slosh factor” of liquid distribution changed? What of our “wobble”.......uh...rotational speed, precession, nutation, and regional perception of the vertical?

    Are we going to have to correct our CNAV texts because earth is changing its distribution of mass and we’ll have lots more non uniformly distributed water sloshing about in funny places....or is it just too many decimal places right of zero.

    My mind is running like the eight year old going why why why.....  like why would all that water come to New England instead of south for a tropical vacation?.... lol...must have boat cabin fever...!

    View and reply to this message

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site