5i6 



NA TURE 



S^Scpt. 30, 1880 



advantages which it is likely to possess. The geographi- 

 cal position of the observatory peak is in longitude 

 121° 36' 40" W., latitude 37" 21' 3" N. 



THE UNITED STATES WEATHER MAPS FOR 

 OCTOBER AND NOVEMBER 1878 



THE Weather Map for October 1878, which 

 appeared in our issue of August 19, showed an 

 area of barometric depression overspreading the whole of 

 the United States except a narrow patch extending from 

 Great Salt Lake northwards. The depression was 

 deepest in the region of Minnesota, where it was o'i5o 

 inch under the average, stretching thence in a west-south- 

 west direction toward San Diego, where it was o'o77 

 inch below the mean. On the Atlantic sea-board of the 

 States, piessure was o'oi4 inch in the south and o'o33 

 inch in the north below the average, and continued 

 relatively low right across the Atlantic, the depression 

 deepening to another minimum over the region including 

 the north-west of Ireland and Scotland, where the greatest 

 defect from the average reached o'220 inch. This wide- 

 spread depression stretched still further to eastward over 

 the whole of Europe, except the extreme north of Scandi- 

 navia, the southern half of Italy, and all Russia, except 

 its north-western provinces ; and to southward at least 

 as far as the equator. Another extensive region of 

 low pressure covered the whole of Asia to the south of 

 a line drawn from Shanghai rcund by Lake Balkash to 

 the Persian Gulf, and extended south-eastward over the 

 ■whole of the East India Islands and Australasia as far 

 as the east coast of New Zealand, where atmospheric 

 pressure rose to the average of the month. Pressure 

 was also much under the average in Cape Colony and 

 Mauritius. 



On the other hand pressure was above the average 

 over the head waters of the Platte and Missouri rivers, 

 and from Vancouver Island northward over the north- 

 west of America, rising to an excess of o'i8o inch in 

 Alaska. But the most important area of high pres- 

 sure covered Greenland, where it rose in the south to 

 o'zJA inch above the mean, and spread to the south-west- 

 ward over Labrador, Newfoundland, and the Dominion 

 of Canada as far as Montreal, and to the eastward over 

 Iceland and the north of Scandinavia. A third area of 

 extensive high pressure embraced the southern half of 

 Italy, Greece, Egypt, Syria, nearly the whole of European 

 Russia, and all Asia to the north of the area of low pres- 

 sure already pointed out. 



The distribution of the temperature anomalies of the 

 month were of the simplest character in their relations to 

 this anomalous distribution of the pressure. In the 

 States to westward of the line of greatest barometric 

 depression a reference to the map will show an extra- 

 ordinary prevalence of strong north-west winds, where, 

 consequently, temperatures were low, the defect from 

 the average being 4"S at Winnipeg, 4°-o on the Platte, 

 3°'6 on the Lower Columbia, and 2'''6 at San Diego. On 

 the other hand, temperatures were everywhere above the 

 average to the east of the Mississippi, the excess being 

 nearly 5^-0 in the New England States, but only about 

 the third of a degree in Florida in the south, and in New- 

 foundland in the north. 



Turning now to the great depression north-west of the 

 British Islands, winds were northerly in Iceland and 

 South Greenland, and there the temperature was re- 

 spectively 2''3 and i°'i below the average. Pressure rose 

 higher from west to east over Europe as far as the Ural 

 River, and into Asia as far as the Tobol, where it was 

 fully o'ico inch above the mean pressure of October. 

 Westerly and southerly winds accordingly ruled, and 

 temperatures were everywhere above the average over 

 this large tract of the earth's surface, the greatest excess 

 being in the basin of the Dnieper, the maximum 7''6 



being recorded at Kiev. Pressure was o'oi3 inch in 

 excess of the average in Syria and Egypt, but the 

 nortlierly winds in Syria indicate a lower pressure south- 

 ward, and in accordance therewith temperature was z^'O 

 at Beyrout and o°-y at Alexandria below the mean. From 

 the rivers Ural and Tobol eastward through Siberia to 

 the Sea of Okhotsk, temperatures were at all places below 

 the average, the defect being from 2^-0 to 3°-o in the 

 basins of the Obi, Yenisei, Amoor, and Peiho. 



It has been stated that pressure was 0-244 '"ch above 

 the average in South Greenland. At the two more 

 northern stations however the excess was only 0-205 '"cli 

 and o'ii2 inch ; and in accordance with this diminution 

 of the pressure northwards over Greenland it is to be 

 noted that whilst in the extreme south of Greenland the 

 temperature was below the average, it rose above it at the 

 stations further north successively to o^'5, 3'^'i, and /^"o. 



November, 1878, the U.S. Weather Map for which 

 accompanies this notice, is memorable as the commence- 

 ment of a period of unprecedentedly cold weather in the 

 British Isles, which was protracted with scarcely even a 

 temporary interruption to the middle of December, 1879. 



In the United States pressure was above the mean to 

 westward of the Mississippi and Missouri, the greatest 

 excess, o'ogo inch, being near the sources of the latter 

 river. Over the rest of the States and Canada pressure 

 was under the average, there being at least three distinct 

 centres of greater depression formed in this extensive 

 region, one over Minnesota and Lake Winnipeg; a 

 second along the St. Lawrence valley, and thence north- 

 ward probably away towards the head of Baffin Bay, the 

 greatest observed defect from the average being o'i3i 

 inch near Anticosti ; and a third along the north of the 

 Gulf of Mexico. In Alaska pressure was fully half an inch 

 below the mean of November. 



But the most marked feature of the month was the 

 development of a region of high pressure in mid-Atlantic 

 and thence northward over Iceland and Greenland ; the 

 greatest excess, 0-362 inch above the average, occurring 

 in the north-west of Iceland. Immediately to eastward 

 an area of low pressure overspread the whole of Europe, 

 rising however to the average on the southern, eastern, 

 and northern, as well as on the western, limits of the 

 continent. Within this extensive depression, just as in 

 the .American depression, were developed several centres 

 of still greater depression, viz., in the Baltic, North Sea, 

 north-west of France, and Corsica. Another area of low 

 pressure extended over India, the Philippine Islands, the 

 East Indian Archipelago, Eastern .Australia, Tasmania, 

 and New Zealand. Over the whole of the rest of Asia, the 

 north and east of Africa, and the south and west of 

 Australia atmospheric pressure was above the average. 



The temperature anomalies in the United States were 

 quite extraordinary. Within and immediately to eastward 

 of the western barometric depression temperatures were 

 from i2°-4 to i3°'7 above the normal for the month, and 

 over this region southerly winds prevailed ; whereas 

 immediately to westward, winds were westerly and 

 northerly, and temperature fell to 3''4 above the normal, 

 and on the Pacific coast to the normal. On the South 

 Atlantic and Gulf States winds were northerly and the 

 temperature only about half a degree above the normal. 

 In connection with the St. Lawrence valley depression, 

 the temperature anomalies were 6'o in the Upper Lake 

 region, 4^-0 in Ohio valley, 3'-6 in the Lower Lake region, 

 and I'-o in the St. Lawrence valley above the normal. 



In the west of Greenland, the pressure anomalies of the 

 three stations proceeding northward were 0-130 inch, 

 0-048 inch above, and 0-016 inch below the mean, and 

 from the strong southerly winds resulting therefrom the 

 temperature anomalies were respectively 6^-8, 9°-o, and 

 9°-5, almost rivalling the relative excesses of temperature 

 which made the weather of this month so meinorable 

 over I:irge portions of the States. As higher pressures 



