68 
NATURE FOR ITS OWN SAKE 
Cloud caps. 
Banner 
clouds, 
from sudden gusts of wind and cold. They 
rush up the mountain-side quite rapidly, as 
everyone knows who has stood there at noon- 
time and felt the draft upward from the valley. 
As soon as they reach the top of the mountain 
they are forced from shelter by the currents 
coming after, and meet with the cold winds 
above the peak. The result is quick condensa- 
tion and the formation of that cloud which is 
called the ‘cloud cap” or ‘‘night cap” of the 
mountain. It is broken and blown away by 
the winds continually, but it is also being con- 
tinually renewed by the ascending currents, so 
that apparently if remains stationary and in- 
tact. It does not sink down, because of its re- 
newal and because the currents in measure lift 
it up. 
Something of the same process is apparent in 
the formation of what is called the ‘banner 
cloud,” which appears to fly out like a streamer 
from some of the Alpine peaks. This cloud is 
{usually on the warm valley-side of the peak. 
The moist air from below rises along this shel- 
tered side to the tip of the peak before it is 
struck by the cold currents and condensed into 
visible vapors. Above it and at the sides the 
cloud is being cut off and drifted away by 
