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Vol. IV, No. 2.] Note on the calm region in the atmosphere, etc. 49 
[N.S.] 
e image passes in a few seconds out of the field of view of the 
‘ees If there is smoke or haze about, as not infrequently 
happens in the cold weather, the balloon is lost for good and the 
observations cease Se that day. In the case I have given, it will 
be seen that between observations 12 and 14 the velocity is greater 
considerably fhan® bot een 9 and ll. In the former case it 
amounts to over 20 miles an hia. whereas in the latter it is onl 
about half of that. Beatie it seems as if the higher velocity 
were lowest, and it is in such cases that unless carefully watched the 
balloon may be lost altogether. But whether these results as re- 
gards magnitude be correct or not, there can be no question as to 
the sudden change of wind direction and velocit y in passing through 
the calm region 
Another point of, I think, first-class importance, emerges from 
the observations I have made in weather which, though not serious- 
ly disturbed, is still not of the settled cold-season type. The settled 
cold w eather is cloudless, and the slight disturbance to which I refer 
is shown by passing clouds. These are usually of two kinds, (1) 
cirrous at a height of probably of 20,000 feet or more. 
across the sky from almost due west, and while within range of 
observation undergo almost no change. They are supposed to be 
due to a disturbance such as takes place in a thunderstorm, 
originating probably in a region of heavy cloud and rain in the west, 
and it may be at a distance of hundreds if not thousands of m 
Moving, as they probably do, with velocities of 30 to 40 miles an 
hour, the moisture which is thrown up in the thunder cumulus to a 
height of, it may be, 20,000 to 30,000 feet, is carried eastward and 
falls slowly in the form of minute crystals. With these high cirrous 
clouds this paper has no connection. But there is a second class 
of cloud which becomes visible occasionally in the cold weather, it 
may be all through the day, but more especially in the evening. 
These are low clouds and have an intimate connection with the 
calm region which I am here discussing. 
Assuming the air movement, at the different levels through 
which the balloon passes, to be horizontal, the curve givi e 
is a good deal of variation, and that above 4,000 feet the general wind 
direction is westerly. If, therefore, a clond is is seen to have a mo- 
tion from the west it would undoubtedly be higher than 4,000 feet, 
whereas a cloud which was at rest or was moving from a direction 
say southerly or northerly, would as certainly not be in the upper 
current. If it were at rest it would certainly be in the calm region, 
and if it had a motion differing considerably from one jemand the 
east it would as certainly be below oe calm re 
Ae. eae be as ee wet Bah | 
iWiU, GLU is GARDEN 
