he temperature decreased reasonably
and consistently with altitude; while fine snow was found falling out
of this upper space into the warmer stream below. Mr. Glaisher discusses
the peculiarity and formation of this stream in terms which will repay
consideration.
"The meeting with this S.W. current is of the highest importance, for it
goes far to explain why England possesses a winter temperature so much
higher than is due to her northern latitude. Our high winter temperature
has hitherto been mostly referred to the influence of the Gulf Stream.
Without doubting the influence of this natural agent, it is necessary to
add the effect of a parallel atmospheric current to the oceanic current
coming from the same region--a true aerial Gulf Stream. This great
energetic current meets with no obstruction in coming to us, or to
Norway, but passes over the level Atlantic without interruption from
mountains. It cannot, however, reach France without crossing Spain and
the lofty range of the Pyrenees, and the effect of these cold mountains
in reducing its temperature is so great that the former country derives
but little warmth from it."
An ascent from Woolwich, arranged as near the equinox of that year
as could be managed, supplied some further remarkable results. The
temperature, which was 45 degrees to begin with, at 4.7 p.m., crept
down fairly steadily till 4,000 feet altitude was registered, when, in a
region of warm fog, it commenced rising abruptly, and at 7,500 feet, in
blue sky, stood at the same reading as when the balloon had risen only
1,500 feet. Then, amid many anomalous vicissitudes, the most curious,
perhaps, was that recorded late in the afternoon, when, at 10,000 feet,
the air was actually warmer than when the ascent began.
That the temperature of the upper air commonly commences to rise
after nightfall as the warmth radiated through day hours off the earth
collects aloft, is a fact well known to the balloonist, and Mr. Glaisher
carried out with considerable success a well-arranged programme for
investigating the facts of the case. Starting from Windsor on an
afternoon of late May, he so arranged matters that his departure from
earth took place about an hour and three quarters before sunset, his
intention being to rise to a definite height, and with as uniform a
speed as possible to time his descent so as to reach earth at the
moment of sundown; and then to re-ascend and descend again m a precisely
similar m
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