Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Lunar Distances with Alex's SNO-T
    From: Alexandre Eremenko
    Date: 2006 Oct 31, 12:51 -0500

    
    Thanks, Fred.
    This seems to be a demo with limited features,
    and I am not sure where on the map elevation
    is shown, and in which units.
    Can you give an example?
    
    Alex
    
    On Tue, 31 Oct 2006, Fred Hebard wrote:
    
    >
    >
    > Alex,
    >
    > The website, http://www.topozone.com/ has topographic maps covering
    > the U.S., from which you can extract your elevation to the nearest 20
    > feet or so, which is close enough.
    >
    > Fred
    >
    > On Oct 31, 2006, at 10:33 AM, Alexandre E Eremenko wrote:
    >
    > >
    > >
    > > Jean-Philippe,
    > > Thanks.
    > > I have no problems with conversion of units,
    > > (though it is sometimes annoying with pressure
    > > for which at least 5 different units are commonly used:
    > > psi(=punds/square inch), millibar(=1000 dynes/square centimeter),
    > > Pascal (not to be confused with psi:-),
    > > inches of mercury and
    > > millimeters of mercury.
    > > And I almost forgot the sixth unit: the atmosphere:-)
    > >
    > > Most barometers on e-bay use one or two of these units,
    > > so one has to hand a conversion table besides the barometer:-)
    > >
    > > Is there a convenient source on the web to find one's altitude
    > > over the sea level, (I mean for those unfortunate ones
    > > who do not live on a sea shore)?
    > >
    > > Alex.
    > >
    > > On Tue, 31 Oct 2006, jean-philippe planas wrote:
    > >
    > >> If you know the elevation of your observation spot as well as the
    > >> atmospheric pressure reduced to sea level (QNH for the pilots) you
    > >> can determine the local pressure (QFE for the pilots) knowing the
    > >> fact that every 28 ft of altitude the pressure decreases by 1
    > >> millibar in the lower standard atmosphere . I'll look for the
    > >> formula in inches of mercury if its the way the weather channel
    > >> provides this info.
    > >>   JPP
    > >>
    > >> Fred Hebard  wrote:
    > >>
    > >> That's correct! I started looking into this, but gave up.
    > >> Hopefully, the physicists will jump in here.
    > >>
    > >> On Oct 31, 2006, at 8:59 AM, Alexandre E Eremenko wrote:
    > >>
    > >>>
    > >>>
    > >>> Fred,
    > >>> I see, this sounds reasonable.
    > >>> But then I need a barometer, or to correct
    > >>> the pressure from the Weather channel for
    > >>> my altitude, because,
    > >>> if I understand correctly, the pressure broadcast
    > >>> for the weather prediction is reduced to the sea level.
    > >>>
    > >>> Alex
    > >>>
    > >>> On Tue, 31 Oct 2006, Fred Hebard wrote:
    > >>>
    > >>>>
    > >>>>
    > >>>> Alex,
    > >>>>
    > >>>> Use the actual pressure. That is the determinant for the refraction
    > >>>> correction. The elevation above sea level has an insignificant
    > >>>> effect on parallax, when you consider that the radius of the
    > >>>> earth is
    > >>>> about 3400 nautical miles, but significantly reduces refraction via
    > >>>> the effect on barometric pressure.
    > >>>>
    > >>>> Fred
    > >>>>
    > >>>> On Oct 31, 2006, at 8:27 AM, Alexandre E Eremenko wrote:
    > >>>>
    > >>>>> Related question: the barometric pressure in the refraction
    > >>>>> formula.
    > >>>>> Should I use the actual pressure at my observation site,
    > >>>>> or should I "reduce it to the sea level"?
    > >>>>> The actual pressure at my site reflects not only the deviation
    > >>>>> from the standard atmosphere but also my altitude over the sea
    > >>>>> level.
    > >>>>>
    > >>>>> Alex
    > >>>>>
    > >>>>
    > >>>>
    > >>>>>
    > >>>
    > >>>
    > >>>>
    > >>
    > >>
    > >>
    > >>
    > >>
    > >>
    > >> JPP
    > >>
    > >> ---------------------------------
    > >> Get your email and see which of your friends are online - Right on
    > >> the  new Yahoo.com
    > >>
    > >>>
    > >
    > >
    > > >
    >
    >
    > >
    
    
    --~--~---------~--~----~------------~-------~--~----~
    To post to this group, send email to NavList@fer3.com
    To unsubscribe, send email to NavList-unsubscribe@fer3.com
    -~----------~----~----~----~------~----~------~--~---
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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