5 66 



NATURE 



{April 15, 1880 



Reverting to the great depression in the Atlantic, we 

 see that it became gradually less and less on proceeding 

 eastward, till at Gibraltar it had risen nearly to the 

 average pressure of April ; but from this point through 

 the Mediterranean a secondary depression was formed, 

 which was deepest over the region lying between, and 

 inclusive of, the Adriatic and Black Seas. Over this 

 region temperature was only the average, whereas to 

 northward temperature rose above the average, the 

 highest excess, 5°"6, occurring in the south of Norway, 

 which was just within the anti-cyclone area of high 

 pressure. To the eastward of the area of low pressure 

 in Western Siberia the temperature rose to 4° - 4 above the 

 average, but along the slopes of the Ural Mountains to west- 

 ward it was only the average, or even slightly below it. 



In May pressure in the United States rose to about the 

 normal in the north-western prairies, but eastward it was 

 lower. The lowest depression, 0070 inch, was about Lake 

 Superior, to west of which, winds being in consequence 

 north-westerl}', temperature fell to from 3°'o to 5°'2 

 below the normal, whilst in the Gulf States, winds being 

 southerly, temperatures ranged from o'5 to 2~'5 above the 

 average. 



The great barometric depression in mid-Atlantic, which 

 was so pronounced a characteristic of the meteorology of 

 April, moved northwards in May to a position immedi- 

 ately to west of Ireland, and was still fully a third of an 

 inch below the average. Between these barometric 

 depressions in the United States and the Atlantic an 

 area of high pressure wedged its way southwards from 

 Greenland, and another high pressure area forced its 

 way northwards from mid-Atlantic about lat. 30°, these 

 two areas being each about a tenth of an inch above the 

 normal. The influence of this distribution of the pressure 

 was a temperature from i c 'o to !3°o above the normal 

 over the British Isles and Western Europe, a lowering 

 of the temperature 2°'5 below the normal in Iceland, and 

 as regards the New England States, a lowering of the 

 high temperature which had prevailed in April to the 

 average in May. 



The low pressure overspread the whole of Europe 

 and the northern slopes of Asia, as far to eastward at 

 least as the Yenisei, except the northern shores of the 

 Mediterranean and a long narrow patch extending from 

 the Black Sea to Riga. A secondary depression was 

 formed in the basin of the Obi and its tributaries, its 

 centre being 0125 inch below the normal. On the east 

 side of this depression, along the Irtish and Yenisei, 

 temperature rose from 4° - 5 to 6" '6 above the average of 

 May, whereas to westward, as at Moscow, it fell to 3 : o 

 below the mean. Thus these barometric depressions in 

 Western Siberia during April and May were fraught with 

 important consequences to the agricultural interests of 

 a large portion of the Russian Empire, extending from 

 the Vistula to the Yenisei. 



The three barometric depressions, viz., those in the 

 United States, in the Atlantic west of Ireland, and in 

 Siberia, were merely centres of increased depression 

 within a wide general depression encircling more than 

 half the globe. From the shores of California eastward 

 through the United States, the North Atlantic, the north 

 of Europe and Asia to the basin of the Yenisei, there 

 stretched a continuous broad region of low pressure ; 

 and it may be added that so far as observations show, 

 another line might be drawn marking out also a con- 

 tinuous low pressure area extending from the Yenisei, 

 through Turkistan, Syria, Egypt, Zanzibar, and Natal, 

 to the Cape. At the same time pressure was above the 

 average over India and Eastern Siberia ; but the greatest 

 rise of pressure had taken place in Australasia, so that 

 whilst in April pressure was C298 inch below the normal 

 in the south-east of New Zealand, in May it was 0122 

 inch above it at Wellington, the increase from the one 

 month to the other being thus 0420 inch. 



Some important changes in the great movements of the 

 atmosphere were brought about in June. Pressure in- 

 creased over the North-Western States and Western 

 prairies, but the greatest depression below the average was 

 now found over the Gulf and Atlantic States, with the in- 

 evitable result of a weakening of the southerly winds of 

 June, an increase of north-westerly, and a lowering of 

 the temperature everywhere, except in the Gulf States, 

 the greatest depression of the temperature being 5° - 6 at 

 Washington. The area of high pressure in the Atlantic 

 increased a tenth of an inch and moved westward about 

 1 5 of longitude, and at the same time extended in area ; the 

 high pressure noted in Greenland in May now covered a 

 wider extent and moved eastward, the greatest excess 

 above the mean being o'i7o inch in the east of Iceland. 

 The high pressure that lay between the Black Sea and 

 Riga now extended westward to Switzerland and east- 

 ward to the upper reaches of the Yenisei. The tempera- 

 ture changes accompanying these great atmospheric 

 movements were a slight lowering of the temperature 

 below the average over the whole of Central Europe, the 

 south-west of Norway, and the east of Scotland, and the 

 raising of the temperature of the whole of the Russian 

 Empire above the average, the excess in the valley of 

 the Kama being 6°'5, and from the Sea of Azov to the 

 head of the Caspian 6°"S. Pressure at the same time fell 

 to some extent under the average along the Mediterranean 

 and north of Africa round to Cape Verd Islands, a change 

 intimately connected with the lowering of the temperature 

 which set in to the northward over Central Europe. 



Pressure continued low over Southern and South-Eastern 

 Africa and in Mauritius, though relatively not so low as 

 in the previous months ; and it had again fallen greatly 

 in Victoria, Tasmania, and New Zealand. The deficiency 

 in the latter islands amounted to 0429 inch, being a rela- 

 tive fall in the mean pressure as compared with May of 

 C561 inch. 



In India pressure in the west still continued above the 

 average, the excess at Kurrachee being 0050 inch ; but 

 in the east it had gone below the normal at Visagapatam, 

 stood near the average at Port Blair, and at little below it 

 at Manila. As regards this part of the globe, the meteor- 

 ological position in June was this ; except a narrow patch 

 of higher pressure extending from the mouth of the Indus 

 southward over the west of India, and thence south-east- 

 ward through Singapore and Batavia to Adelaide, South 

 Australia, pressure would appear to have been under the 

 average from Cape Vcrd Islands, round by the Mediter- 

 ranean, Black, Caspian, and Aral Seas, Tashkent, 

 Shanghai, New Zealand, Australia and the Cape. 



In July pressure was under the normal in the United 

 States and Greenland, with two centres of greater depres- 

 sion, one in the north of Greenland and the other about 

 the Rocky Mountains south of lat. 40^. The influence of 

 this arrangement of pressure, as regards the United 

 States, was an increased prevalence and strength of 

 southerly winds to east of the Rocky Mountains, ac- 

 companied with a temperature from one to three degrees 

 above the average of July, and a rainfall considerably 

 above the average ; whereas on the Pacific coast N.W. 

 winds were in excess, and the temperature in Oregon 

 was 2°7, and at San Uiego l°"o below the mean. 



From the north coast of South America, and thence 

 stretching to north-east as far as the north of Iceland 

 and Christiansund in Norway, lay a broad extensive 

 region of very high pressure, embracing within its 

 northern limits the whole of the British Isles, the north of 

 France, Belgium, Holland, and a thin strip of the south- 

 west of Norway, the centre being in mid- Atlantic about 

 lat. 35 and long. 35°. In the British Islands tempera- 

 ture was above the average, the greatest excess being 

 2 C 'S in the north of England. 



Another extensive area of pressure, above the July aver- 

 age, overspread India and extended towards the north-east, 



