REPORT ON ATMOSPHERIC CIRCULATION. 65 



As pressure has still further fallen in the anticyclone of the North Atlantic and 

 risen rapidly in Asia, the difference in pressure is now so small that the westerly winds 

 from the Atlantic towards the centre of the old continent may be considered at an 

 end for the year. But the cyclonic area over the North Atlantic has now extended 

 and deepened to such an extent as to rule the winds of western and northern Europe. 

 With the greater prevalence of these south-westerly winds the rainfall of these regions 

 is largely increased, reaching even to the annual maximum in Denmark and a con- 

 siderable portion of Finland and Sweden. 



October. — The mean temperature has fallen to -5° in the extreme north of Green, 

 land, and except a portion of the North Atlantic and the north of Scandinavia 

 temperature is now below 32° over the whole of the Arctic regions. This low 

 temperature descends to lat. 54° on the coast of Labrador, and to the same latitude in 

 eastern Siberia. The abnormally high temperatures have now altogether disappeared 

 from Spain, Greece, and Scandinavia, and, as regards the last region, the isothermals 

 show that abnormally low temperatures from the north-east begin to overspread it. 



The fall of temperature in the interior of Asia is very great, being from 20° to 30° 

 over a wide area. At Werkojansk the fall is from 3 2° '7 to -0 o, 6, or a fall of 33° - 3. 

 On the other hand, in Egypt, Syria, and over the Red Sea it is very small. 



The highest isothermals are 90° in North and South Africa and in the north of 

 Australia, and 85° in Brazil and Central America. 



Pressure has fallen over the whole of the southern hemisphere, over the Atlantic, 

 Greenland, and the western half of Europe, to the west of a line drawn from Corfu to 

 Helsinfors, and thence north-eastwards to Franz Josef's Land ; and the cyclonic region 

 of the North Pacific has further extended and deepened. Everywhere else pressure 

 has increased, particularly over Asia, being the maximum monthly increase that occurs 

 in any month anywhere over the globe. In the centre of the continent the increase is 

 from 0-25 to 0-30 inch. Thus, in passing from September to October, pressure 

 diminishes over all those regions where the temperature, relatively to that of immedi- 

 ately surrounding regions, is higher in October than it was in the month previous ; but 

 it increases over those regions where temperature is relatively lower, and most so just 

 over those regions where the temperature is now most strikingly low as compared with 

 adjoining regions. 



The area in the Arctic regions covered by a pressure exceeding 29 "9 5 inches, 

 the average for the globe, is now largely extended. In addition to the four anti- 

 cyclones in the Atlantic and Pacific, anticyclones appear in Asia, where the isobars 

 show a pressure of 30-20 inches; in the Indian Ocean, with a pressure equally high. 

 There are also less marked ones in the Pacific Ocean midway between South America 

 and Australia ; in the United States to the east of the Mississippi ; and in Spain. 



The cyclonic areas of low pressure in the north of the Atlantic and Pacific have 



(PHVS. CHEM. CHALL. EXP. — fART V. — 1889.) 6 C 



