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Old Apr 28, 2012, 03:10 PM
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Would that clouds indicate a good thermal day ?


Hi

Today temperature was at 20deg Celsius, wind blowing at 17km/h and rain was forecasted for late afternoon.

When I went out, clouds (cumulus ?) was scatered all over the sky and it seemed that something (thermals?) moved their tops upwards in the sky. Unfortunately, couldn't go flying, as I still built my glider.

Could this clouds indicate a good thermal flying day ?
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Old Apr 28, 2012, 03:19 PM
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Have a bunch of Buzzards around my house here that seem to use thermals to great effect regardless of cloud conditions.
Old Apr 28, 2012, 04:18 PM
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Buzzards are good to follow.... also, I'd highly recommend Secrets of Thermal Soaring from Radio Carbon Art.
Old Apr 28, 2012, 04:43 PM
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I would prefer a book, rather than dvd. Are there any books around ?

Buzzards are rare, in our fields. We have plenty of seagulls though
Last edited by FRIDAY_2008; Apr 28, 2012 at 05:03 PM.
Old Apr 28, 2012, 05:19 PM
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Originally Posted by FRIDAY_2008 View Post
I would prefer a book, rather than dvd. Are there any books around ?

Buzzards are rare, in our fields. We have plenty of seagulls though
You ain't gonna believe this but....http://www.amazon.com/Old-Buzzards-S.../dp/B000CC7FJ0
Old Apr 28, 2012, 05:23 PM
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Try this one for the book.

http://carstensbookstore.com/oldbusobobyd.html
Old Apr 28, 2012, 06:22 PM
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Clouds and Thermals.......


Friday2008- To specifically answer the stated question that you asked:

Yes, the pictures you presented show a sky full of air moving up(and down), so if it looks like that, it usually is good flying for me where I live in Corvallis, Oregon, USA. Some of my best thermal climbing has been done in skies that look like that. Of course, thermals are not limited to skies/cloud conditions that look like that, but generally if the sky looks like your pictures, it should be a good day for thermals.

As far as books go, another good book is:
"Understanding the Sky" by Dennis Pagan. It's occassionally technical and sometimes you need to read sentences 2-5 times before fully grasping, but that's because what the atmosphere is doing at any time is rather complicated. This book is specifically for pilots, R/C pilots, sailplane pilots, hang-gliders, etc.

Adios -Paul
Old Apr 28, 2012, 07:05 PM
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Thanks Paul,
I downloaded "Understanding The Sky" in PDF format here

David
Old Apr 28, 2012, 07:23 PM
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Low cumulious clouds like these. I was up for 40 munites today, and could have stayed up a lot longer.

Bob in Seattle
Old Apr 28, 2012, 08:31 PM
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Low cumulious clouds like these. I was up for 40 munites today, and could have stayed up a lot longer.

Bob in Seattle
Those are absolutely beautiful clouds Bob.

Well captured.
Old Apr 28, 2012, 09:04 PM
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Ha - just bought a copy! Had to be done.

Thanks for the link.
Old Apr 28, 2012, 09:49 PM
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Thanks Rich. The fun never ends.

Bob in Seattle
Old Apr 28, 2012, 10:33 PM
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FRIDAY_2008:

Clouds can indeed indicate lift, and your pictures show some typical examples.

Typical clouds that result from thermals have puffy, rising tops and flat, dark bottoms. But be aware: there can be thermals even under a featureless layer of stratus clouds.

In my experience, seagulls will fly slope lift, but seldom thermal lift. That's just my experience, if someone else has seen them fly thermals, well there you are. Buzzards (as mentioned), hawks, crows and ravens will fly thermal lift and fly it well. There must be hawks, ravens and crows in Greece, especially up in the mountains.

Swallows won't fly thermal lift, but are good thermal indicators. They chase insects, and if there are swallows on a field and they all start climbing, it's because a thermal has lifted the insects. I know there are swallows in Greece.

I hope you get your airplane built soon.

Yours, Greg
Old Apr 29, 2012, 02:40 AM
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Thanks for the links guys.

As for the birds, we have them all in Greece, but just not in Athens. We fly 8miles far from sea and seagulls are often visitors. The place we are flying has a little slope while the rest is flat. Crows are also present, but in much smaller numbers.

I ve seen seagulls though rocketing towards sky. Actually they start from near the slop to the rest of the field in search of thermals and back.
Old Apr 29, 2012, 03:22 AM
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Days when clouds will form are nice but its the time of day when clouds start to form that is great for RC gliders. As the sun is warming the air near the surface (and its moisture) the air is rising. Later on these days there are lots of clouds.
I like to look at an hour by hour forcast and fly during a period of the most heat gain, usualy starting around 10AM to 2 in the afternoon. Work rarely allows this though!


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