18 THE AIR 



Other Meteorological Phenomena. 



Clouds may be observed to perfection at sea, where 

 nothing interferes with the wide prospect from horizon 

 to horizon. There are three main types of clouds : 

 cirriform, or wisp clouds ; cumuliform, or heap clouds ; 

 stratiform, or layer clouds. Different classifiers of 

 clouds have subdivided these main types into several 

 varieties, and it would be a useful exercise to compare 

 the different classes, which have for the most part been 

 made from observations at a shore-station in temperate 

 latitudes, with the forms seen at sea in all parts of the 

 world. 



For many purposes the broad division into three 

 types suffices. It is noteworthy that one type of cloud 

 prevails more than the other in certain ocean localities. 

 In the north-east trade region great masses of stratus 

 abound, while in the south-east trade district the 

 cumuliform predominates. In the doldrums and the 

 horse latitudes the cumulus type prevails, often in the 

 most curious and remarkable forms. In the north- 

 east trades cirriform clouds are constantly to be seen 

 moving away to the north-east from a south-westerly 

 direction. 



Fogs are of such serious importance in navigation 

 that they are naturally objects of much interest at 

 sea. Certain regions are almost constantly beset by 

 fog — off the Newfoundland Banks, for instance, where 

 the icebergs brought down by the cold water from the 

 north meet the warm water coming from the south. 

 Fogs are common, also, in the corresponding districts of 

 the North Pacific and off the Falkland Islands, where 

 similar causes operate. Dense fogs frequently occur 

 round the coasts of England in the early winter months, 





