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    Re: U.S. Standard Atmosphere Supplements
    From: Fred Hebard
    Date: 2005 Aug 27, 00:51 -0400

    On Aug 27, 2005, at 12:34 AM, Frank Reed wrote:
    
    > Marcel, you wrote:
    > "The U.S. Standard  Atmosphere Supplements, 1966 (possibly also in a
    > newer
    > edition) includes  tables of temperature, pressure, density etc. for
    > five
    > northern latitudes  (15, 30, 45, 60, 75), for summer (July?) and winter
    > (January?) conditions as  a function of height."
    >
    > I think you'll find that the US Standard  Atmosphere is mostly
    > relevant to
    > very high altitude issues like  supersonic/hypersonic flight and
    > spacecraft
    > re-entries (and in fact if you  search for this title on google image
    > search
    > you'll discover photos of its cover  art which shows a satellite
    > orbiting the
    > Earth). For refraction near the  horizon, you need details on the
    > lower troposphere
    > which is really a weather  issue. And as such you can find data on it
    > from
    > weather resources. Today, I did  a sample calculation based on today's
    > and
    > yesterday's weather balloon data from  Chatham, Massachusetts USA. You
    > can access
    > plots of this data here:  http://weather.unisys.com/upper_air/skew/.
    >
    > I converted these data into  lapse rate models as follows:
    > Mean Lrate on both days: -6.0 deg C per km from  0 to 13km, 0 above
    > that.
    > For August 26:
    > Lapse Rate,  Upper Limit  (m)
    > 0, 200
    > -6.5, 2050
    > -2.6, 4375
    > -6.7, 6625
    > -8, 11000
    > -5,  13000
    > 0, >13000
    > For August 27:
    > Lapse Rate,  Upper Limit  (m)
    > 25, 200
    > -6.5, 2050
    > -5.3, 5100
    > -8, 8450
    > -7.4, 10750
    > -4.9,  13000
    > 0, >13000
    >
    > Next taking the profiles, I can generate the  atmospheric density as a
    > function of altitude and from that the refraction  table. As usual,
    > all of this
    > structure has no impact above about 3 degrees of  altitude. Below 3
    > degrees
    > altitude, there are significant differences in  refraction as follows:
    > Alt(deg), mean ref, ref on 8/26, ref on  8/27:
    > 0,  35.02, 42.23, 36.32
    > 0.5, 29.07, 30.57, 29.43
    > 1, 24.57,  25.08, 24.74
    > 1.5, 21.11, 21.33, 21.2
    > 2, 18.39, 18.49, 18.44
    > 2.5, 16.21,  16.27, 16.24
    > 3, 14.44, 14.47, 14.46
    > 3.5, 12.99, 13.01, 13.00
    > 4, 11.77,  11.79, 11.78
    > 4.5, 10.75, 10.76, 10.75
    > 5, 9.88, 9.88, 9.88
    > The "mean  ref" column is the refraction in minutes of arc calculated
    > from a
    > simple  constant lapse rate of -6.0 degrees from sea level up to 13km.
    > The
    > other columns  are the calculated refraction in minutes of arc for
    > yesterday and
    > today based on  the lapse rate profiles described above. At the time
    > of the
    > balloon flights (0h  GMT), these refraction tables very likely would
    > have
    > corresponded closely to  actual observations. But the real point is
    > simply to
    > demonstrate the sort of  daily variability that we should expect and
    > to indicate
    > where this variability  arises and the fact that we can calculate it
    > if desired.
    > Atmospheric refraction  is no mystery, but the atmosphere is a messy
    > place,
    > even on a sunny  day.
    >
    > -FER
    > 42.0N 87.7W, or 41.4N  72.1W.
    > www.HistoricalAtlas.com/lunars
    >
    >
    
    Frank (or should I say, Frank I :),
    
    That's very nice evidence for the anomalous dip that George Huxtable is
    so fond of mentioning, wouldn't you say?  The most convincing
    demonstration I have seen at least.  I wonder how far below "ref" the
    refraction at 0 degrees altitude would go.  Seven minutes above is
    astounding.
    
    Fred
    
    
    

       
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