We were able to check the data the balloon collected in real time as the balloon rose. The figure to the left is a screenshot that shows temperature (red), pressure (green), and relative humidity (blue) as a function of time (the vertical axis). Notice that the balloon rose more slowly after 900seconds, as seen in the change in the slopes of the temperature (red) and pressure (green) curves. The slowdown happened right after the balloon passed through a cloud (see the relative humidity curve). This seemed to indicate an icing problem. As the temperature is below zero Celsius, ice can stick to the balloon, weighing it down. Our balloon survived though, reaching at least 20hPa, as Liping told us later.That was OUR sonde, Nov. 21, 12UTC, from Gan Island.Monday, November 21, 2011
A balloon launch
Today, we (Tammy Weckwerth, Jean-Philllippe Duvel, Adam Sobel and I) had a tour of the ARM mobile facility with Liping Deng and launched a weather balloon with our signatures on it. ARM is the Atmospheric Radiation Measurement program (now part of the Atmospheric System Research program) of the Department of Energy.
We were able to visually track the balloon as it rose to as far as 300hPa (~9km). It took more than half an hour and was quite remarkable: the balloon was reflective enough that it looked like a little star in the sky, and even twinkled a bit from time to time. I lost track of the balloon after 300hPa but Jean-Phillippe apparently could still see it...
We were able to check the data the balloon collected in real time as the balloon rose. The figure to the left is a screenshot that shows temperature (red), pressure (green), and relative humidity (blue) as a function of time (the vertical axis). Notice that the balloon rose more slowly after 900seconds, as seen in the change in the slopes of the temperature (red) and pressure (green) curves. The slowdown happened right after the balloon passed through a cloud (see the relative humidity curve). This seemed to indicate an icing problem. As the temperature is below zero Celsius, ice can stick to the balloon, weighing it down. Our balloon survived though, reaching at least 20hPa, as Liping told us later.That was OUR sonde, Nov. 21, 12UTC, from Gan Island.
We were able to check the data the balloon collected in real time as the balloon rose. The figure to the left is a screenshot that shows temperature (red), pressure (green), and relative humidity (blue) as a function of time (the vertical axis). Notice that the balloon rose more slowly after 900seconds, as seen in the change in the slopes of the temperature (red) and pressure (green) curves. The slowdown happened right after the balloon passed through a cloud (see the relative humidity curve). This seemed to indicate an icing problem. As the temperature is below zero Celsius, ice can stick to the balloon, weighing it down. Our balloon survived though, reaching at least 20hPa, as Liping told us later.That was OUR sonde, Nov. 21, 12UTC, from Gan Island.
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I found this really interesting. We've been releasing balloons for years and always wondered about the speed they rise and cloud conditions.
ReplyDeleteI'd never considered ice forming on the balloon.
I guess this balloon was large?
Thanks
david@balloon.com
Thanks for the comment, David. The balloon was about 6 feet tall and 4 feet wide and that is a typical size for these balloons. Icing on the balloons apparently is quite common. People in the DYNAMO project have tried putting oliver oil on the the balloon (!) to mitigate this problem, but I don't know how well it worked...
ReplyDeleteCheers,
Zhiming
Thanks for the prompt reply.
ReplyDeleteWe've always thought that the balloon expands as it rises, the theory is it becomes brittle and shatters as it expands at altitude.
Do you agree with this (do you under inflate the 6ft balloon to allow for expanding later).
Hi David,
ReplyDeleteYou are absolutely right that the balloon expands as it rises, which causes it to pop eventually, and the sonde to fall to the ground. People certainly don't inflate the balloons to this point before launch.