tag:blogger.com,1999:blog-20110414.post3308648798463475741..comments2023-09-28T09:00:44.681-10:00Comments on Wind Lines: Da Vinci DecodedUnknownnoreply@blogger.comBlogger5125tag:blogger.com,1999:blog-20110414.post-70625876165012268962007-04-13T15:10:00.000-10:002007-04-13T15:10:00.000-10:00One other thing is those vertical dew point lines ...One other thing is those vertical dew point lines - shouldn't they curve 1 degree every 1000 feet? The dewpoint doesn't stay constant but drops down with less pressure as shown in <A HREF="http://www.csgnetwork.com/estcloudbasecalc.html" REL="nofollow">CloudCalc</A> . <BR/><BR/>Dewpoint only stays constant if the pressure does, and less air pressure can hold less water. Well now I am confused about whether to tilt those dp curves left, right or not, but you will be less rusty on the subject and can sort it. The thermal slope should close on dewpoint lines by 4.5 per 1000feet but have an absolute slope of 5.5?launch potatohttps://www.blogger.com/profile/16181256927892325561noreply@blogger.comtag:blogger.com,1999:blog-20110414.post-2187710850315314202007-04-13T11:58:00.000-10:002007-04-13T11:58:00.000-10:00Nice tool and summary. I used to run a similar too...Nice tool and summary. I used to run a similar tool in TX for our flatland sailplane site and our low PG hill. Quite accurate for high aerotowed SP, but I couldn't make it correlate much to low level footlaunch conditions. So take my comments for what they're worth, the voice of forecasting failure speaking to the voice of success :)<BR/><BR/>We had a distant upwind and downwind sounding station in contrasting microclimates. In that case it helped to average the quite different results of the two; averaging the balloon readings was suggested as even better. Some say to favor the upwind side due to the time delay. Hilo is questionable though. Although sometimes upwind for the lower airmass, I think the balloon then rides air flowing up the saddle between volcanos. You can see weird numbers suggesting land effects (and I've paraglided there - weird zone).<BR/><BR/>Another issue is the temperature gap between background and thermal. A big one may not correlate to strength. Look at the 2pm curves, and you may often see the incremental filling in of the background temp to match your lower temp lines like 80 degree. At least in the high flatland case the thermals push up the heat, so the next thermals have to be hotter to have much boost. Hill case may be different, but an elevated trigger point violates some assumptions of these curves anyway.<BR/><BR/>You wondered if the SP-standard 3 degrees was enough for a thermal to support a PG. May be sufficient, because I don't think your tool is accounting for humidity of thermal vs dryer elevated air. In areas of high dewpoint like here, it can account for further 4 degrees according to "virtual temp" paragraph of <A HREF="http://www.soarforecast.com/README.html" REL="nofollow">readme</A> . Moist air is buoyant (lots of H2), although maybe you won't reach much dryer upper air. Also note their "thermal index" paragraph, which downplays the factors of temp differences in favor of height of convection - I've heard that is nearly a consensus, at least at non-mountain sites.launch potatohttps://www.blogger.com/profile/16181256927892325561noreply@blogger.comtag:blogger.com,1999:blog-20110414.post-82342259624866689742007-04-13T07:54:00.000-10:002007-04-13T07:54:00.000-10:00Two people have complained that they can't post co...Two people have complained that they can't post comments to this article - if you are having trouble posting, please call me at 223-0144 so I can help you troubleshoot the problem - I'd really like to figure it out. Thanks!Alexhttps://www.blogger.com/profile/06249789335111913420noreply@blogger.comtag:blogger.com,1999:blog-20110414.post-2013323710285880352007-04-13T07:15:00.000-10:002007-04-13T07:15:00.000-10:00Doug, Thanks for taking the ime to explain all the...Doug, Thanks for taking the ime to explain all the lines. Really appreciate you sharing your thermal tool. It's still gonna take me a little whle to understand it though.Waianae Jimhttps://www.blogger.com/profile/15275430122119016694noreply@blogger.comtag:blogger.com,1999:blog-20110414.post-85033628522878134732007-04-13T00:05:00.000-10:002007-04-13T00:05:00.000-10:00Doug, this is great. I've been following along as ...Doug, this is great. I've been following along as you've developed your tool over the past few months, and trying my best to make sense of it all, but I have to admit I've been a little fuzzy on some points, and this posting is a very nice and clear explanation of what each part represents.Alexhttps://www.blogger.com/profile/06249789335111913420noreply@blogger.com