I think there’s a pretty big difference. Attenuation occurs at varying rates depending on the nature of the atmosphere the UV is traveling through at the time, but it does occur all the way to the ground; all else being equal, shorter wavelengths are absorbed higher up; long-wavelength UVA makes it pretty much all the way to MSL.
https://www.sciencedirect.com/science/article/pii/S1011134496000188 For the 200-300 nm range Nizar mentioned, my guess is that the attenuation between 100k’ and MSL is ~95% or more. That’s just a hunch though. But I’m certain that the increased UV damages the balloon on a microscopic level more at altitude than at MSL. Whether it plays a measurable role in the time-to-burst, who knows. Sounds like a good experiment for a future flight (though I’ve no idea how you’d control it!). 73 de N5OL Sent from my iPhone > On Mar 22, 2019, at 8:29 PM, Jonathan Guthrie via BVARC <[email protected]> > wrote: > > I don't believe there is a significant difference in UV radiation between > 100,000 feet or so and the ground. Plastics at ground level that are > intended to be exposed to direct sunlight for long periods of time routinely > have UV protection added to them. > >> On 3/22/19 9:56 AM, NIzar Mullani via BVARC wrote: >> Ravi, >> >> Glad you mentioned UV radiation as a heating source. I had not thought about >> this before. As we get into rarefied air, the very short wavelength UV light >> in the 200 to 300 nm range could also become very damaging to the >> superficial layers of material. >> >> I wonder if anyone has looked into how this extra short UV radiation effects >> balloon materials, and, whether it plays a role in the longevity of balloon >> material! >> >> Nizar >> >> From: BVARC [mailto:[email protected]] On Behalf Of Ravi Patrick >> Ratnala via BVARC >> Sent: Thursday, March 21, 2019 5:11 PM >> To: BRAZOS VALLEY AMATEUR RADIO CLUB >> Cc: Ravi Patrick Ratnala; [email protected]; >> [email protected]; [email protected]; john Parmalee; >> [email protected]; [email protected] >> Subject: Re: [BVARC] Especially for those that won’t be able to make it to >> the Houston HamFest this weekend . PLEASE REPOST >> >> Sounds like y'all are talking about moving through the tropopause; from the >> troposphere, and upward through the stratosphere. Temperature decreases >> (generally) with altitude in the troposphere, because this region is ruled >> by thermal heating of the ground (and associated boundary layer), >> convection, and adibatic expansion. Once you get into the stratosphere, >> temperature increases with altitude due to heating by UV radiation. >> (Obviously this is a short form description.) >> >> 73, Ravi >> >> On 3/21/2019 1:16 PM, Bruce via BVARC wrote: >> i would have thought as the balloon gets higher with thinner air that the >> temperature would get colder. you say it goes up. interesting. i may need >> to take a look at that. neat experiment. >> >> 73...bruce >> >> Sent from my iPhone >> >> On Mar 21, 2019, at 1:10 PM, john Parmalee via BVARC <[email protected]> wrote: >> >> >> Especially for those that won’t be able to make it to the Houston HamFest >> this weekend. >> >> Two Balloon launches with ham gear on board. You can participate. >> >> Live video of both launches https://zoom.us/i/2815436502 >> >> 9:30 AM BLT-51 will launch >> >> You can track with http://APRS.fi search the call W5ACM-10. >> >> You can Google APRS to find the site. >> >> BLT-51 will be a floater, designed to be tracked via APRS and glide across >> the country, and hopefully even further. The last one went to Florida in >> about six hours. >> >> Around 1:00 PM another launch BLT-52 >> >> BLT-52 is a “popper.” Designed to go up as high as possible and burst, also >> to be tracked via APRS. Last August a popper flew to nearly 100,000 feet. >> “To the edge of space.” >> >> W5ACM Cross-band FM repeater will be in board with with >> >> Input on 147.435 MHz ß-----à Output on 446.550 MHz no tone, open to all >> to work >> >> A WB8ELK APRS Tracker on 144.390 MHz with the call W5ACM-11 will be on >> board. >> >> You can track at http://APRS.fi search for W5ACM-11 >> >> On board also the AB5SS Smart Beeper on 10 and 20M 14.318 & 28.322 mHz, the >> temperature in CW call sign and BL-52. Wach as the balloon passes through >> 60,000 feet the Temperature to rise. >> >> The video will also be recorded for later playback as well, and depending on >> the size of the captures, they will either be in the groups.io FILES area >> https://groups.io/g/Ham-Radio-Tech-Notes/files , or my website.K5WH.net >> >> . >> >> _______________________________________________ >> BVARC mailing list >> Radio,Radio,Radio We are a radio Club! >> Talk it up! On the air about every event, every meeting, every net, every >> time, talk about the club, ham fests, events and people. >> [email protected] >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >> Message delivered to [email protected] >> >> >> _______________________________________________ >> BVARC mailing list >> Radio,Radio,Radio We are a radio Club! >> Talk it up! On the air about every event, every meeting, every net, every >> time, talk about the club, ham fests, events and people. >> [email protected] >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >> Message delivered to [email protected] >> >> >> >> _______________________________________________ >> BVARC mailing list >> Radio,Radio,Radio We are a radio Club! >> Talk it up! On the air about every event, every meeting, every net, every >> time, talk about the club, ham fests, events and people. >> [email protected] >> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org >> Message delivered to [email protected] > > -- > Jonathan Guthrie > ARS KA8KPN > _______________________________________________ > BVARC mailing list > Radio,Radio,Radio We are a radio Club! > Talk it up! On the air about every event, every meeting, every net, every > time, talk about the club, ham fests, events and people. > [email protected] > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > Message delivered to [email protected]
_______________________________________________ BVARC mailing list Radio,Radio,Radio We are a radio Club! Talk it up! On the air about every event, every meeting, every net, every time, talk about the club, ham fests, events and people. [email protected] http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org Message delivered to [email protected]
