DISCUSSION AND ANALYSIS OP WINDS. 



673 



measured with accuracy, which prevent all winds from reaching the same velocity 

 even if the relative distance of the isobars be the same.- 



These conditions must be considered in brief. 



In the lowest stratum the velocity is lessened on account of friction on the sur- 

 face of the earth, while the higher are also more or less affected by the friction of 

 the different strata on each other. 



The winds on the ocean will be less affected in this way, because of the smooth 

 surface of the water. The greater velocity of the wind on the sea is well known. 

 The figures published in the " Quarterly Weather Reports" of the Meteorological 

 Office, of London, very clearly show the decrease of velocity in the interior of 

 Great Britain even in level parts of the country. 



The following table shows this for the United States. I give the mean velocity 

 of the wind in a group of inland stations (Eastern New York) compared with that 

 of the sea-coast (Cape Cod and adjacent islands) and also with tliQ summit of 

 Mount Washington, the highest peak of the Isew England States. 



Mean Velocity of the Wind. Miles per Hour. 





Summer. 



Winter. 









w 





W 





^ 





^ 





W 





W 





^" 





^ 





fe 



^ 



2.4 



CO 



5.1 



ai 

 5.7 



CO 



5.4 



4-5 



fc 



5.8 



fe 



w 

 3.3 



03 



10.4 



ID 



7.9 



5.7 



8.7 



a 



Eastern New York . . 



4.1 



2.S 



5.1 



4.8 



7.5 



Mount Washiugtoni . . 



19.5 







17.4 



21.0 



17.3 



15.5 



24.3 



50.2 



41.7 



36.8 



38.8 



41.8 



34.0 



44. S 



52.2 



Cape Cod and islands . 



7.8 



10.9 



5.3 



9.0 



6.7 



9.6 



9.3 



6.3 



19.9 



20.5 



12.2 



16.1 



10.6 



10.9 



10.9 



20.0 



Mount Washington having the freest position, the strength of the winds there 

 must be considered as more nearly normal than at the other places. The N. W. 

 winds are the strongest, both summer and winter. But in the vicinity of Cape 

 Cod, the N. E. winds coming over the smoother surface of the sea, are the 

 strongest. 



It is safe to present the following rules for the velocity of the wind. It is greater: 



1. On high isolated peaks, than at low stations. 



2. On the seashore, and especially on isolated islands, than in the interior of 

 continents. 



3. In level countries than in countries surrounded by mountains. 



4. In prairies, and especially desert countries, than in wooded regions. 



These rules apply to the local positions only. But we may remark that it is 

 possible to mention some regions where the velocity of the winds is greater, others 

 where it is less, than the average over the whole earth. 



To the latter belong the equatorial calm-belt, and the calm-belts at the polar 

 limits of the trade-winds. It would be wrong to imagine that any point on the 



' One summer and two winters, 1870-71, and January, February, and December, 1872. 

 85 July, 1875. 



