METEOROLOGY. 



485 



" 5. The mean of the monthly and annual extreme temperatures as 

 well as the resulting non-periodic variation of temperature within each 

 month and the whole year. 



"6. The absolute highest and lowest temperatures that occur within 

 a given interval of time ; the length of this interval should also be given. 



" 7. The mean variability of the temperature, as expressed by the dif- 

 ference of consecutive daily means and by the frequency of such changes 

 in temperature arranged according to definite scale, e. g., from 2 to 2 

 degrees. 



" 8. Mean limit or date of frosts in spring and fall, and the number of 

 days free from frosts. 



" As m ost of the published long series of temperature observations 

 refer to stations within cities, it is also necessary to have in mind the 

 systematic differences between city and country temperatures, the for- 

 mer being generally warmer. The above requisites for complete eliina- 

 tological study are exemplified in the following table based on observa- 

 tions within the city of Vienna: 



Table I. — Characteristics of the temperature of the air in the city of Vienna. 



{Temperatures by centigrade scale. Latitude, 48° 12' north.; longitude, 16° 22' east of Greenwich. 



Altitude, 194 meters J. 



Month. 



Monthly 

 means. 



5gS 



s-2 



a>> 



OS 



3 S 



r; - 



c a 

 2 a 



Means from ob- 

 servations for 

 20 years, at 

 the respective 

 hours — 



Daily vari- 

 ation of I 

 temperature 

 from 

 20 years of 

 observation. 

 I I 



9 & 



© <D 



as 



X I 



a: i 



December 

 January . . 

 February . 



March 



April 



May 



June 



July 



August . . . 

 September 

 October... 

 November 



Tear. . 



-0.8, 

 -1.3 

 0.4 

 4.2 

 10.0 

 15.1 

 18.6 

 20.3 

 19.6 

 16.1 

 10.5 

 3.7 



-0.3 

 -1.7 



0.1 



4.3 



9.9, 



15.1] 



18.81 

 20.5 

 19.7 

 13.9 

 10.0 

 3.9, 



2.3 

 2. 5 

 2.2 

 1.8 

 1.7 

 1.5 

 1.2 

 1.3 

 1.3 

 1.2 

 1.4 

 1.4 



-1.5 



-2.3 



-1.2 



1.6 



6.2 



11.4 



15.5 



16.9 



16.0 



12.2 



7.7 



2.5 



0.6: 



0.3 

 2.6 

 7.4 

 14.0 

 19.3 

 22.4 

 24. 3 

 23.7 

 20.4 

 14.3 

 5.5 



-1.0 



-1.6 



0.1 



3.6 



9.0 



13.8 



17.1 



18.9 



18.2 



14.8 



9.5 



3.3 



2.1 



2.7 

 3.8 

 5.9 

 7.8 

 8. 2| 

 7.6 

 7.9 

 7.9 

 8.2 

 6.6 

 3.1 



4.7 

 4.9 

 6.11 

 7.8' 

 9.6 



10.2 

 9.9 



10.1 

 9.7 

 9.6 

 8.3 

 4.9 



9.7 

 11.4 

 16. 7 

 23.9 

 28.5 

 31.5 

 32.6 

 32.9 

 28.3 

 23.2 

 14.9 



-11.2 

 -12.1 

 -10.0 



- 5.9 



- 1.0 

 2.7 

 9.1 



11.0 

 9.8 

 4.9 

 0.6 



- 5.9 



20.8 

 21.8 

 21.4 

 22.6 

 24.9 

 25.8 

 22.4 

 21.6 

 23.1 

 23.4 

 22.6 

 20.8 



19.1 -22.6 2.0 

 18. 8 1 -25.5 2.1 

 20.0, -20.0 



24. rr 

 28.8 

 36.0 

 37.8 

 38.8 

 37.5 

 33.5 

 27.1 

 21.3 



0. 74 7. 1 



12. 9 8. 



5.9 8.0 33.9,-15.1, 49.0 



38.8 



-13.3 



-7.0 



-1.6 



3.8 



8.0 



5.6 



-0.6 



-6.8 



-15.0 



2.0 

 1.8 

 1.9 

 1.8 

 1.9 

 1.9 

 1.8 

 1.7 

 1.5 

 1.8 



-25.5*1.9 



" II. The elements of radiant heat that are important as climatologic 

 factors cannot be stated so definitely as are those of air temperature. 

 It would appear that we need to know the energy and the totality of 

 the two radiations, i. e., that received from the sun and that given out 

 by terrestrial objects, but unfortunately thus far satisfactory observa- 

 tions of these phenomena are almost wholly wanting; even the appa- 

 ratus proper for the measurements is as yet too crude to be available for 

 accurate work. The solar radiations possess no such differences among 

 themselves as to justify the terms ' heat rays,' ' light rays,' ' chemical' or 



