120 H. MOHN. METEOROLOGY. [2nd. ARC. EXP. FR AM 



THE INTERDIURNAL VARIABILITY OF THE TEMPERATURE 



OF THE AIR. 



Taking the difference between the daily mean temperature of one 

 day (Tables, pp. 63 — 107) and that of the next, and then the mean of 

 the differences for rising and falling temperatures for each month, we 

 obtain the numbers in the first two columns in the Table below. The 

 thii'd column gives the weighted mean of the first two columns. The 

 monthly numbers of cases or days with rising and with falling diurnal 

 temperatures are in the 4*'' and 5*^^ columns. 



Temperature 



rising 



falling 



Mean 

 of I and 2 



Temperature 



rising 



falling 



3—1902 



January 



February — — . . 



March — — . . 



April — — . . 



May — — . . 



June _ — . . 



July - - . . 



August 1900 — 1901 . . 

 September 1898, 1900—01 



October 1898 — 1901 . . 



November — — . . 



December — — . . 



2.74 

 4.02 



3-04 



2.17 



1. 14 



1. 12 



1.29 



1.32 

 2.48 

 2.97 

 2.81 



99 

 53 

 93 

 33 

 99 

 02 

 10 

 08 



73 

 86 



73 

 14 



2.87 

 3-78 

 3-15 

 2.71 

 2.09 

 1.09 

 I. II 

 1. 17 



1-55 

 2.72 

 2.83 

 2.97 



Days 



I5.75 



13-25 



15 



16 



18 



18.75 



14-5 



13 



13 



13-5 



13 



15-5 



Days 



15-25 



14-75 



15 



14 



13 



11.25 



16.5 

 18 



17 

 17-5 

 17 

 15-5 



Mean and Total 



2-37 



29 



2-34 



179-25 



185-75 



The columns 1, 2 and 3 show a very decided annual period. The 

 interdiurnal variability is greatest in the winter time; the maximum lies 

 in February, and the minimum in June. The mean rising for the year 

 is a little greater than the falhng. The time during which the tempe- 

 rature is rising, is shorter than its time of falling; it rises more quickly 

 than it falls. 



