38 
Köppen-Heft der Annalen der Hydrographie usw. 1926. 
exist in the summer when the air depressions in the Western Mediterranean are 
few or nome at all. At that season the correlation between the pressure of Ice- 
land and that of the Western Mediterranean is reduced to — 2. 
My purpose is, therefore, to suggest that in seeking for centres of action 
we should have regard to the normal excess of sea-temperature above air-tem- 
perature rather than the salient features, high or low, of the normal distribution 
of pressure. 
It would be of interest in this connexion to examine the conditions of the 
middle latitudes of the southern hemisphere in respect of the difference of tem- 
perature of sea and air, because in those regions the normal distribution of 
pressure indicates a circle of low pressure near the latitude of 60° S, instead of 
the centres of low pressure near that latitude in the North Atlantie and North 
Pacifio. We have not found data enough to work out the conditions for so high 
a southern latitude. The most noticeable example of exocess of sea temperature 
over air temperature that we have been able to identify is in 30° S latitude 
and 110° E longitude during the months of May to Oetober.