346 
CLINE. 
warmth gained dynamically when the descent has been 
rapid. Horizontal layers or currents of dry or moist, hot 
or cold air interposed upon each other with the lines divid¬ 
ing them sharply defined have been noted by observers in 
balloon ascensions, and the study of these phenomena in 
this investigation appears to demonstrate that vertical cur¬ 
rents may have as sharply defined boundaries, so far as their 
conditions in relation to the general atmosphere are con¬ 
cerned, as have been observed in connection with horizontal 
currents. 
These hot winds are more frequent between the 34th and 
45th parallels of latitude than to the north or south of this 
territory. This results from the southern portions of the 
V shaped depressions resting generally over this section. 
The conditions with which hot winds generally occur over 
this section are shown in plate 4. The hot winds to the 
south of the 34th parallel occur with the development of 
secondary low-pressure areas, as represented by plate 6. 
Those to the north of the 46th parallel accompany condi¬ 
tions similar to those which produce the chinook in winter, 
namely, the low pressure to the north of the Dakotas and 
Minnesota, with the high pressure over the northern plateau 
region and extending back toward the Pacific coast, as 
represented by plate 5. The conditions which produce 
the hot winds over the last two sections of the territory 
named are more rare than the conditions which produce 
them over that portion between the 34th and 46th parallels 
of latitude, hence hot winds are not frequent over these sec¬ 
tions. 
Winds similar in some respects to those general warm 
winds which occur over the eastern slope may be experi¬ 
enced with a less degree of heat, but intensely dry over the 
central valleys and even occasional^ eastward on the 
Atlantic seaboard. Such winds are likely to occur when 
there is a high pressure area over the gulf and south Atlan¬ 
tic States, another along the Pacific coast, and-two or three 
low pressure areas slowly follow each other in succession 
