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Observation Pioneers
Wed Nov 23, 2005
Listen in RealAudio 
Hi, I'm Bryan Yeaton for The Weather Notebook.
In September 1783, the Montgolfier brothers filled a balloon with hot air and created the
first craft to lift humans skyward. Over the succeeding decades, several manned balloon
flights measured the atmosphere, but none was as ambitious as the flight that was proposed by
Frenchmen Barral and Bixio in 1850. They intended to ascend to 40 thousand feet to study how
temperature, solar energy and atmospheric composition varied with increasing altitude.
Their first flight in late June was a complete failure. Their hydrogen-filled balloon ascended
with such incredible initial speed, it over-stretched the balloon fabric. Unfortunately, its
rigging was made too short, and the rapidly expanding gas bag pushed down into the passenger
basket, almost asphyxiating the men. While attempting to vent gas to slow their ascent, they
punctured the balloon. They had risen to 17,000 feet, but now plummeted earthward, crashing
miraculously unhurt into a vineyard just five minutes after launch.
Four weeks later, July 27th, Barral and Bixio launched successfully. Ascending to 8,000 feet,
they began to enter a large cloud. Rising through the 15,000-ft thick cloud, they were
astonished to watch the temperature drop. At 23,000 ft, the apex of their five-hour flight,
the thermometer bottomed out at minus 38F, the surrounding air filled with ice
needles.
As the pair soared into the intense white sunlight above the cloud, they witnessed a mock sun
formed by the reflection of the sun's image off ice crystals floating in the cloud's upper
reaches below them. This was the first-ever witnessed during flight.
The Weather Notebook is a production of The Mount Washington Observatory. We are generously
supported by Subaru of America and the National Scienc
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