the Mean Annual Temperature Variation. 491 



The following diagram (fig. 3) gives an interpretation of 

 the detailed curve. Yig. 3. 



- ^ 



^ /s/s \ \ \ v 



<> 



2/' / * 2\N 



***** * 



The variation is composed of phases 1, 2, 3, and 4 belonging 

 to four concordant curves. The steps occur approximately 

 at the following dates : Jan. 25, March 9, April 22, Oct. 2, 

 Nov. 29, and Dec. 16. 



Then, during the summer, on the contrary, from June 9th 

 till July 28th, we have practically a straight line of mean 

 temperatures increasing from 17°'6 to 19°'3 C. This line 6 

 is evidently discordant : it cuts all the others. The summer 

 maximum is 3° below the maximum which would be observed 

 if curve 4 were fully developed. The summer temperature 

 may therefore be considered abnormally low. Now, between 

 6 and 4 we observe the fragments of a curve 5 extending from 

 May 22nd to June 8th and July 29th to Aug. 26th. This 

 curve intersects all the others : its amplitude is evidently 

 much smaller than the amplitude of curves 1-4. 



Although the temperature curve for Warsaw may be con- 

 sidered a most typical example of these normal anomalies 

 of the annual temperature variation, the breaks being too 

 well accentuated to be ascribed to chance circumstances, it is 

 useful to cite a few other examples in order to show how, 

 gradually, we pass from one type of variation to another. 



Hellmann has published * a detailed curve of the daily 

 means derived from the observations made in Berlin during 

 the years 1848-1907. Referring to the diagram for Warsaw 

 (fig. 3), the Berlin curve displays the fragments 1-4, 5 is 

 missing, and 6 is a well-developed curve extending from 

 June 13th to Sept. 21st, with a maximum on July 22nd. 



* Preuss. Met. lnst.,Abk. vol. iii. No. 6, Berlin, 1910. 

 2 M 2 



