-VARIABILITY OF 



TEMPERATURE 

 AFRICA. 



IN SOUTH 



By J. R. Sutton M.A., F.R.Met.S. 



It has been pointed out before* that in expressing the terms repre- 

 senting the climate of a place, it is necessary to give, in addition to 

 the elements of maximum and minimum, mean, and range of 

 temperature, what is known as the mean inter-diurnal variability of 

 temperature, that is to say, the mean difference between the tempera- 

 tures of one day to the next. The present paper is a contribution 

 to this work for South Africa, giving the variability for three typical 

 stations, namely, for Durban, East London, and Kenilworth (Kimber- 

 ley), of the maximum and minimum temperatures for each month 

 for each station, from ten years' observations, together with the 

 variability of dew-point and relative humidity at Kenilworth at the 

 hours 2 a.m. and 2 p.m. 



The mean monthly values of the inter-diurnal variability for 

 Durban are : — 



Table i. — Variability of Temperature at Durban, 



1895 to 1904. 



It appears from this that the variability of maximum temperature 

 at Durban is greatest in the early summer, at least at mid-winter. 

 This result is brought about chiefly by the frequent warm and 

 occasional very hot (foehn) winds of September to December. 

 Generally speaking, the temperature of one day at Durban is pretty 

 much like the next ; but a hot wind means in nearly every case a 

 sudden rise from the normal maximum one day and an equally rapid 

 fall the next, such pairs of values of great variability making a 

 considerable addition to what would otherwise be the mean variability 

 of the month. It is quite a mistake, though a common one, to 



*See inter alia, Hann, Lchrbtich der Met., 1901, p 115; Ward, "Suggestions as 

 to a more Rational Climatology," Report of the Eighth Geographic Congress, 

 1905, p. 280. 



