334 THE PHYSICAL GEOGRAPHY OF THE SEA. 



the winter is the most famous season for these gales. That is the 

 time when the Gulf Stream has brought the heat of summer and 

 placed it (§ 84) in closest proximity to the extremest cold of the 

 north. And there would therefore, it would seem, be a conflict 

 between these extremes ; consequently, great disturbances in the 

 air, and a violent rush from the cold to the warm. 



953. In like manner, the gales that most prevail in the extra- 

 tropics of the southern hemisphere come from the pole and the 

 west, i. e.^ southwest. 



954. Storm and Eain Charts for the Atlantic Ocean have al- 

 ready been published by the Observatory, and others for the whole 

 seas are in process of construction. The object of such charts is 

 to show the directions and relative frequency of gales in all parts 

 of the sea, the relative frequency of calms, fogs, rain, thunder, and 

 lightning. 



955. These charts are very instructive. They show that that 

 half of the atmospherical coating of the earth which covers the 

 northern hemisphere — if w^e may take as a type of the whole what 

 occurs on either side of the equator in the Atlantic Ocean — is in 

 a much less stable condition than that which covers the southern. 



956. There are, as a rule, more rains, more gales of wind, more 

 calms, more fogs, and more thunder and lightning in the North 

 than in the South Atlantic. These phenomena at equal distances 

 from the equator north and south, and for every 5° of latitude, 

 have been compared (Plate XIII.) ; that is, all the storms, calms, 

 rains, etc., between the parallels of 25° and 30° N., for instance, 

 have been compared with the same between the parallels of 25° 

 and -30° S. ; those for January north being compared with those 

 for January south, and so on for each month, between all the five 

 degree (5°, 10°, 15°, etc.) parallels from the equator to 60° N. 

 and S. 



957. In some places here and there, and in some months now 

 and then, there may be more gales, as in the neighborhood of Cape 

 Horn, in the South than in the North Atlantic ; but such cases 

 constitute the exceptions — they are by no means the rule. Cape 

 Horn, in the South Atlantic, and the Gulf Stream, in the North, 

 furnish seats for agents which are very marked in their workings. 



