F. Waldo— Rise and Fall of the Wind in the U. 8. 285 
Art. XXII.— The Relations of the Diurnal Rise and Fall of 
the Wind in the United States; by FRANK WALDo. 
I. Relative Rapidity of Diurnal Rise and Fall of Wind. 
AN inspection of the curves indicating the diurnal change in 
the wind velocities shows usually at a glance whether the rise 
of the wind to the mid-day maximum takes place more rapidly 
or more slowly than the subsequent fall of the wind. 
For January over nearly the whole of the United States 
_ the rate of fall of the wind‘is more rapid than the rate of rise 
toward the mid-day maximum. Still in the western U. S. 
there is a central region extending from northern New Mexico 
to Montana and a region in the extreme southwest in southern 
California and southwestern Arizona where the rise is more 
rapid than the fall; and in a number of places irregularly dis- 
tributed the rates of rise and fall are equal; while in the 
eastern part of the U.S., in the Ohio valley, there is a small 
section where the rise and fall are about equal, and around this 
there is a narrow region where the rise is more rapid than the 
fall. 
For July the fall of the wind is in general more rapid than 
the rise: but in the western U.S. there are regions, in western 
Colorado and eastern Utah, in northern Texas, Oklahoma and 
southern Kansas, and on the central and southern Pacific coast, 
where the rise is more rapid than the fall; while also in the 
eastern U.S., in central Ohio and at some places on the Atlan- 
tic coast the rise is more rapid than the fall. The places 
where the rise and fall are equal are not so numerous in July 
as in January. 
For the Year, to the east of the medial meridian of the 
U.S. (about the 100° longitude) the fall of the wind after the 
mid-day maximum is more rapid than the rise preceding it: 
but to the west of this line the rise of the wind proceeds at a 
more rapid rate than the fall. There are, however, some 
exceptions to this rule. Over a limited region in southern 
Oregon and northwestern Nevada, and again in southeastern 
Arizona and southwestern New Mexico, the fall of the wind is 
more rapid than its rise. Also on the central Mississippi River 
and around Lake Erie the rise of the wind is more rapid than 
its fall. 
II. Period of Mid-day Rise of Wind. 
The duration of the period when a deceded continuous rise 
of the wind occurs towards the nearly mid-day maximum 
