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    Re: Lunars barometric pressure correction
    From: Frank Reed
    Date: 2005 Apr 19, 20:45 EDT

    Bill, you wrote:
    "The consensus seemed to be  that local-station barometric pressures were
    corrected to sea-level pressures  before broadcast (and barometers were
    likewise adjusted to show sea-level  pressures for their permanent location
    above sea level) .  When using  your Lunars Calculator, would it behoove the
    user to correct from reported  sea-level pressure to local pressure?"
    
    Yes, if you're at an unusually  high altitude above sea level, then you
    should multiply typical "weather report"  barometric pressures by
    exp(-altitude/34,000 feet)  [roughly].   Assuming you're staying in the same place, you will
    only have to calculate this  once. For an altitude of 1000 feet above sea level,
    this factor would be 97.1%.  This will make almost no difference --only a
    tenth of a minute of arc for  altitudes below 20 degrees, two-tenths below 10
    degrees. If you go for a sail on  Lake Titicaca, the world's highest navigable
    lake, the factor is 69% and you'll  have measurable changes in refraction at all
    altitudes below 70  degrees.
    
    -FER
    http://www.HistoricalAtlas.com/lunars
    
    
    

       
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