THE FRESH-WATER LOCHS OF SCOTLAND. 



419 



the surface current, directly produced by the wind, carrying the warm 

 surface water along with it, and the return current, to take the place 

 of the water blown along the loch, is spread throughout the whole depth 



200 " 



1 +3 +4 0-6 *' 4-7" + S" #?* ^0 $l" 52" 53* 54* 

 FIG. 69. TYPICAL MONTHLY CURVES OF TEMPERATURE IN LOCH NESS. 



of the loch. But when the discontinuity layer has formed, the loch is 

 divided into two current systems. Above the discontinuity layer there 

 is the surface current produced by the wind, and the return current also 

 takes place above the discontinuity layer, without directly affecting the 



