Sierra Club Bulletin 



Vol. VIII San Francisco, June, 1911 No. 2 



LITTLE STUDIES IN THE YOSEMITE VALLEY 



By F. E. Matthes. 



III. The Winds of the Yosemite Valley.* 

 To most folks roaming about the Yosemite Valley its 

 winds and breezes seem a matter of small interest or 

 consequence. They come and go, now one way, now 

 another, apparently without regularity or system, — moody, 

 capricious beyond analysis. In the midst of the grand 

 tumult of the Yosemite landscape, our senses fairly be- 

 wildered with its many glories, we cannot stop to con- 

 sider these little breaths that blow about us, and let them 

 puff by unheeded. The Yosemite region is not a windy 

 country anyway ; but once or twice in a season does a gale 

 arise to disturb its wonted tranquillity, and its daily 

 zephyrs are such light, airy little nothings as to scarcely 

 seem worthy of downright study. And yet they become 

 singularly interesting when once rightly understood. 

 They turn out to be surprisingly systematic and withal so 

 intimately connected with the configuration of the valley 

 itself, that, to one who has at length mastered their secret 

 they grow to be one of its immanent features, as char- 

 acteristic and inseparable as El Capitan or the Yosemite 

 Falls. 



It happens to be so ordained in nature that the sun shall 

 heat the ground more rapidly than the air. And so it 

 comes that every slope or hillside basking in the morning 

 sun soon becomes itself a source of heat. It gradually 

 warms the air immediately over it, and, the latter, becom- 

 ing lighter, begins to rise. But not vertically upward, 

 for above it is still the cool air pressing down. Up along 

 the warm slope it ascends, much as shown by the arrows 

 in the accompanying diagram ( Fig. i ) . Few visitors to 



*Published by permission of the Director of the U. S. Geological Survey. 



