io8 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. JO 



in rings, heavy rings for positive and light for negative anomalies/ 

 The pressure gradients are also given by arrows for stations of the 

 British Isles and also for Hamburg. See further details in the 

 explanation of the tables. 



In plates i6 to 41, we have drawn on the left hand pages at the 



99 1900 I ? 3 4 5 6 7 8 9 1910 



Figure 48. The curves give the mean values for all six 10° longitude fields 

 a.long the route Channel to Ncw^ York. B : the air pressure gradients for 

 January-February, February-March, and for the mean value for the months 

 January, February, and March indicated by a strong dotted line. W : the 

 anomalies of the surface temperatures. L: the anomalies of the air tempera- 

 tures. W-L : the anomalies of the difference: surface temperature minus 

 air temperature. W, L, and W-L apply for February as indicated by weak 

 full-drawn lines, for March-April as indicated by weak dotted lines, and for 

 the mean values of both decade groups, February and March-April, as indi- 

 cated by strong lines. 



bottom curves for the year, which give the local variations of the 

 air pressure gradients across the Atlantic Ocean (curve B). The 

 January curves are given by weak dotted lines, the February curves 



^ The normal temperatures for all these stations, with the exception of 

 Liepe's stations, are computed for the same interval of time, 1900 to 1910, as 

 for our fields. 



