DISCUSSION AND ANALYSIS OF WINDS. 729 



A moderate prevalence of S. W. winds extending also to S. E., S., and W 

 seems to be the real state of the case when local influences are eliminated (See 

 Plate 7.) 



Until within a few years we knew next to nothing in regard to the winds in the 

 basin of the Jenisei. Middendorff had expressed the opinion that the S. W. winds 

 of Europe extended to the lower Jenisei, but there were not facts enough to sustain 

 his opinion. The observations at Krasnojarsk showed that this was the case on 

 the middle part of the river, while Jenisseisk, situated more to the N., has pre- 

 vailing S. E. winds. This is caused by a change in the direction of the Jenissei 

 from the mouth of the Angara ; it flows from S. E., and, as at other points, the 

 winds from the upper part of the river are prevailing. 



It will be seen that the winds of the summer are very different from those of 

 winter. The flow of air towards the depression of central Asia is the principal 

 feature at this season. In Siberia we have the influence of the Arctic Ocean, 

 which is principally felt. It is especially the Kara Sea with the Obi Bay, 

 extending further southward than other parts of the Polar Sea, which we must 

 consider. It must be remembered that the steppes and deserts of central Asia 

 are not separated by any barrier from the Arctic Ocean, in the meridian of 

 western Siberia, so that the air of the Arctic flows freely towards those countries 

 with their high temperature and low pressure. In comparing the table given here 

 for western Siberia with that for European Russia, it will be seen that N., N. E., 

 and N. W. winds are much more frequent in the same latitudes in Siberia. In 

 this the influence of the Arctic Ocean is to be seen, although westerly winds 

 from the Atlantic Ocean also extend there. Pressure is not steady on the Arctic 

 Ocean, its fluctuations are great even in summer, and when a storm-centre passes 

 over it, the air from the Atlantic Ocean and southern Europe will be drawn in to 

 supply the deficiency, as a S. W., W. or N. W. wind. 



In summer central Asia has the same winds as western Siberia, W. and N. W., 

 while in winter the difference is great. This is clearly shown on Plates 5 and 6. 

 Semipalatinsk, being situated in the division of zone 50°— 53°, has a system of winds 

 intermediate between western Siberia and central Asia, the E. being the most fre- 

 quent in winter, but southerly winds also occur. 



Further south, on the lower Syr-Daria, at Taschkent and at Krasnovodsk (on 

 the eastern shore of the Caspian) N. E. winds largely prevail in winter. That this 

 is also the case in other parts of central Asia, where no long-continued observations 

 have been made, is the report of nearly all the scientific travellers who have visited 

 this country.^ 



In the prevalence of easterly winds Central Asia resembles the steppes of Southern 

 Russia, but there are two important differences. First, the winds are more north- 

 erly ; second, they prevail to a much greater extent. In Central Asia the mean 

 direction in winter is between N. and E., while in southern Russia it is between 

 S. and E., Astrachan and Orenburg excepted, but these places are already on the 

 border of central Asia. The reason of this difference of the two regions seems 



' I refer, for example, to Khanikof, Basiner, Helmersen, Severtzof. 



92 July, 1875. 



