38 Mr. E. Gold : Relation between Periodic Variations of 



The following values for the phases of the semi-diurnal 

 pressure and temperature variations have been calculated 

 from published observations : — 



Kew. Valencia. Ben Nevis Ben Nevis Equator Pic du Midi 

 (1343 m.). (Summer). (Ocean). (2860 m.). 



Pressure 



. 146° 



140° 



130° 



116° 



156° 



124° 



Temperature .. 



42° 



42° 



50° 



86° 



84° 



80° 



Difference 



. 104° 



98° 



80° 



30° 



72° 



44° 



The observations agree, therefore, as well as could be 

 expected with the theoretical result. 



[Note. — The value of 8° for the retardation of phase for the Eiffel 

 Tower was taken from a paper by Jaerisch, Met. Zeit. 1967, and appears- 

 to have been calculated by Hann from the earliest observations. Later 

 results give for the retardation only 2°, see Angot, Annates du Bureau 

 Meteor ologique, 1894, Part I. This of course affects the values of c, (3. 

 I have, therefore, taken the results given by Hann (Lehrbuch, p. 602) 

 for high-level stations, and assumed the phase at sea-level corresponding 

 to them to be 150°. I have also calculated for the same period (summer) 

 the difference of phase between Ben Nevis and Fort William. The 

 results are plotted in the accompanying diagram, in which the curve 



Connexion between the decrease of phase in the semi-diurnal 

 pressure wave and the height. 



40 



§ 30 

 «* 20 



1 













8 



WfADF 



'.STE/H 



SAWr/6 





• 



/% 



''e/SSENBSRG 







S/iltuMCH 









1000 



2000 



300077Z- 



represents the equation 6=c(l— e-^~) for c=15, /3 = 2.10~ 6 . The 

 temperature amplitudes at sea-level would be reduced owing to this 

 change in the values of c, /3 in the ratio of 3 to 5. The general con- 

 clusions will not, however, be affected. The decrease in the semi- 

 diurnal temperature amplitude with increase of height will be slower 

 than that given in the table below. 



