Io6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. JO 



of the isobar directions. In the open ocean south of 50° north 

 latitude, however, where one ought not to expect that outside 

 influences should be so important, we find a definite relation between 

 the directions of the average isobars and the average isotherms. 

 This proves nothing with certainty concerning the general tendency 

 of the winds to create ocean currents particularly as we see that 

 in the open ocean north of 50° north latitude the relation does not 

 hold, and in the ocean southwest of Ireland we must assume that 

 the surface current goes toward the left of the isobar directions 

 and not towards the right (see the arrows in fig. 7). However, 

 the peculiar relation pointed out between the isobar direction and 

 the isotherm direction in the middle part of the North Atlantic Ocean 

 points to the fact that the wind here bears a strong influence on 

 the motion of the surface waters. We must in this case therefore 

 expect that it has also a strong influence on the variations of the 

 surface temperature in consequence of its tendency to displace the 

 water-masses on the surface. 



COMPARISON OF THE VALUES OF THE AIR PRESSURE GRADIENT 

 WITH THE TEMPERATURE ANOMALIES 



In tables 12 D and 13 D we give for the months of January and 

 February in each year the values found for the deviations of the 

 isobars from the normal direction in each of the 10° longitude 

 fields. Also the reciprocals of the values of the intensity of the air 

 pressure gradients as well as numbers obtained by multiplying these 

 intensities by the sines of the angles of deviation of the isobars. 

 These values are also given for the months of January and February 

 for the resultant between the directions of the isooars for these 

 months. For the northerly route, Channel to New York, the same 

 values are given for the month of March. Since the values for 

 the mean gradient efifect for January and February are obtained by 

 vector analysis from the resultant for the isobar directions of these 

 months, the results obtained are not always equal to the mean of the 

 values of the two months. 



On the chart for February and for March-April of the different 

 years (see pis. 16 to 41) we give for each of our 10° longitude 

 fields arrows whose direction and magnitude indicate the re- 

 sultants for the isobar directions and the air pressure gradients.* 



^ It must be recalled that the charts for February show the following : 

 Air pressure. The arrows for the ocean fields (see pi. 15, i to 24, and pis. 

 I to 7) give the results for January and February. The arrow^s for the other 



