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We learned here that the refraction tables of Pub. No. 249 and the Air
Almanac are copies out of the article "The Refraction Table in the Air
Almanac" by D.H. Sadler in Vol. 5 (1952) of the (then) "Journal of the Royal
Institute of Navigation".



For all those, who do not have access to the paper,  here the input data
which Sadler used for his calculations:



Standard atmosphere at sea level: Temperature 15degC and pressure
1013.2mBar.

Lapse rate: -6.5degK/km until 11'000m.



Refraction coefficient: 1.00028208; it was intended to use a value of
1.0002718. A footnote explains:



"The value actually used as the basis of the integrations was 1.00028208,
corresponding, as far as mu(o) is concerned, to a temperature of 10deg C
instead of 15deg C. This numerical error, which has been found only in
checking the manuscript of this paper, will (fortunately) lead to no
appreciable error in the published table. Values of Ro should be decreased
by 1 part in 56. Alternatively the table can be corrected by adopting the
values of Ro unchanged and changing (by a maximum of 5?) the critical values
of the temperature. In view of the smallness of the corrections, the table
will be kept unchanged until the more fundamental tables become available."



I hope that this is of use to all those who try to understand the content of
this table.



Marcel

   

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