!28 



fairly certain that, at least as regards the semi-diurnal East com- 

 ponent, the values for x, and y, above 4 km. respectively' increase 

 and diminish, which comes to this that the phase runs from the 

 second quadrant to the fourth through the third. 



Considering the manner the curves are drawn on the graph, the 

 following is arrived at for amplitude and phase. 



Semidiurnal variation. 



As has been mentioned previously, the results obtained for the 

 lower layers (below 4 km.) are strongly affected by land and sea 

 breezes and the Espy-Köppen effect and only after final reduction 

 of the observations above the Java Sea we may look forward to a 

 better insight into the wind movement in these layers. 



From the wind records of the Noordwachter lighthouse 50 m. 

 above sea level, the following particulars have been derived for the 

 semi-diurnal variation of the East component : 



July— November 13 sin (2^—160°) 



July— September 23 sin (2^—176°) 



This value will probably for the greater part be free from the 

 Espy-Köppen effect, but not quite from the influence of land and 

 sea breezes, as the amplitude for the diurnal term amounts to 0.84 m 

 and undoubtedly it will be accompanied b}' a semi diurnal one, 

 as has been discussed previously for the analogical case at Batavia. 



The graphic, however, distinctly indicates the presumable course 

 of the curves between and 4 km and this cour.se is opposite to 

 the one above 4 km. 



The surface value of the phase, i. e. 180°, given above, agrees 



