DISCUSSION AND ANALYSIS OF WINDS. 



689 



place for the year 1872. (Zone 13, No. 13.) Even at stations on the Gulf coast, 

 there are scarcely any land winds (N., N. W. and A¥.) observed in summer, which 

 would be the case if there was a regular alternation of land and sea breezes. 



North of Texas, throughout the whole region between 34° and 44° N. and the 

 Eocky Mountains and Mississippi, the winds have also monsoon features, but more 

 subdued. The prevailing winds of this region are N. and N. W. in winter and S. 

 in summer. The cause is the same as in Arizona, New Mexico, and Texas. There 

 are some irregularities in the mountain region (Central Colorado) but east of the 

 mountains, in Nebraska and Iowa, the general character is again strongly marked. 

 It is less the case in S. E. Minnesota, but even there the winds are southerly in 

 summer, and deflected to the S. E. by the direction of the Mississippi Valley. In 

 N. E. Arkansas and in Missouri the difference between winter and summer is 

 still less marked. This is an approach to the character of the region between 

 the Mississippi and the Appalachian chain, where there is no difference whatever 

 between the seasons, the mean direction being about W. S. W. the whole year 

 round. (See Plate 8.) 



The tables for this work were printed before the results of observations on two 

 high peaks of the Rocky Mountains could be obtained, both over 14,000 feet high. 

 A meteorological station was established on Pike's Peak in the end of 1873, by the 

 United States Signal Service, and the " Report for 1874" contains the means of 

 observations for the first twelve months. I have given them in percentages, adding 

 the station of Colorado Springs, at the eastern base of Pike's Peak. On Mount 

 Lincoln the observations were made under Professor Hayden's geological survey of 

 the territories, from 21st July, 1871, to the end of January, 1874. Both Pike's 

 Peak and Mount Lincoln are situated in the central part of Colorado, 





Summer. 







Winter. 









a 



4 

 8 



2 

 6 



in 1 m 



12 

 31 



7 

 21 



■a 



31 



8 



3.0 



14 

 36 



3 



0.4 

 22 



2 



0.8 



1 



H 



19 

 1 



O.G 



5 



1 

 



6 



21 



1 



8 

 34 



9 



24 

 27 

 30 



Colorado Springs . . . . 

 Pike's Pealc . . . . ' . 

 Mount Lincoln 



Colorado Springs .... 



Pike's Peak 



Mount Lincoln 



2 

 4 



10 

 5 



33 



6 



Spring. 



Autamn. 



31 



20 



8 

 1.5 



4 

 1.5 



20 

 2 



16 



7 



4 

 28 



7 

 27 



10 

 14 



20 



15 



' 



5 



0.7 



9 



11 



32 



The difference between Pike's Peak and Colorado Springs seems to give a much 

 greater proportion of S. W. and W. winds at the higher station, and a smaller 

 amount of N., especially in summer. This agrees with the generally entertained 

 opinion as to the prevailing direction of the upper atmospheric current from the 

 W. S. W. in the middle and northern latitudes. In any case more observations are 

 necessary in this respect. 



The mean direction of the wind in the region north of Texas is: — 



87 July, 1875. 



