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Old Apr 21, 2013, 11:28 PM
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Windsor, Canada, near Detroit
Joined Jul 2007
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thermals, and stranger things...

i have been flying my planes for many years, but it has been in warm weather...until now.
in those years, i got into thermals regularly, and grew under the impression that it had to be warm weather in order to climb with the help of hot air (the so called 'thermals'). but recently i have been flying near freezing, and have witnessed my planes climbing and staying up there for a long time. some say that is the differential temperature that makes air go up. that is, if there is air at, let's say, -20c, and surrounding air is -10c, that mass of air will go up. so if in freezing air, and then we encounter not-so-freezing air, that makes planes go (or stay) up there, why call them 'thermals'? shouldn't be more correct to call them something like 'rising air'? or 'risers'?

whatever you experts may suggest...
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Old Apr 22, 2013, 04:52 AM
flying since 2000
sfluck's Avatar
Winterthur ZH, Switzerland
Joined Mar 2009
496 Posts
everything is relative. relative to the -20c air, the -10c air is relatively hot.

As i understand the term "Thermal", I don't associate it with warm or hot, so it fits perfectly for cold, but slightly warmer air as well.
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Old Apr 22, 2013, 04:58 AM
ahh crap! crunch..
atmosteve's Avatar
Australia, QLD, Fraser Island
Joined Nov 2007
3,864 Posts
Sfluck is wise. That's how it goes. I could go on and talk a lot of crap but that happens to often here and it wouldn't alter the fact of temp differentials across a certain scale of practical flying temps. Flying in that kind of temp makes any flyer a special kind of breed to me!
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Old Apr 22, 2013, 05:21 AM
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etymologies

thank you guys for your contributions.
i was referring to the origin of the word etymologically.
the original word comes from greek: therme=heat. see:
i found this in etymologies:
from Greek therme "heat," from PIE *ghwerm-/*ghworm- "warm" (cf. Latin fornax "an oven, kiln," formus "warm," Old English wearm; see warm). Sense of "having to do with heat" is first recorded 1837. The noun meaning "rising current of relatively warm air" is recorded from 1933.

and the last 1 brings the key word (relative), as i mentioned when i said that it is the differential temperature. 'relatively warm air' means that what matters is that some mass of air is warmer than the surroundings.

still, i was asking if the word used makes sense, and we could use another that defines better what is really going on?
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Old Apr 22, 2013, 05:46 AM
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Windsor, Canada, near Detroit
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depends on where you live

Quote:
Originally Posted by atmosteve View Post
Sfluck is wise. That's how it goes. I could go on and talk a lot of crap but that happens to often here and it wouldn't alter the fact of temp differentials across a certain scale of practical flying temps. Flying in that kind of temp makes any flyer a special kind of breed to me!
well, lucky you that lives in warm weather. but if you live up north, as i do, you have to decide: fly when there is not too much wind-or don't fly.
and the temperature? well,up here it is cold for quite some time during the year, and winter is getting longer with this global weather thing, so we have to choose to fly in cold weather, or fly not.
that's why i choose to fly in cold weather, and have learned about these 'thermals' in cold weather.
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Old Apr 22, 2013, 06:01 AM
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sfluck's Avatar
Winterthur ZH, Switzerland
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Quote:
Originally Posted by phil alvirez View Post
still, i was asking if the word used makes sense, and we could use another that defines better what is really going on?
Nice idea, but why? When you say "Thermal" everybody knows what it is, if you say "Riser" everybody may look out for gliding traffic up there.

But I don't want to be a party pooper here, if the new term is funny and catchy why not
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Old Apr 22, 2013, 07:49 AM
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Windsor, Canada, near Detroit
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a better word

Quote:
Originally Posted by sfluck View Post
Nice idea, but why? When you say "Thermal" everybody knows what it is, if you say "Riser" everybody may look out for gliding traffic up there.

But I don't want to be a party pooper here, if the new term is funny and catchy why not
agree. but for newcomers nothing is right or wrong: they learn the way the guys before them talk.
and for all the others, doing something by many, and/or for a long time, does not justify it.
still, i was just thinking of using a word that means something closer to reality.
and about a better word, i was only suggesting something, but it is open to all to bring ideas. this way probably we could find it.
but trying to make sense may be asking too much.
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Old Apr 22, 2013, 08:39 AM
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Maryland
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When compared to absolute zero -20 is hot! (0 Kelvin = -273 C)
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Old Apr 22, 2013, 09:22 AM
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United States, IN, Indianapolis
Joined Feb 2004
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I think we should call them giddy-up. As in "I just ran into a big giddy-up and she was at cloud base in no time".

There are a lot of things in this world where the name doesn't make perfect sense. Normally people just go with it. RAM is Random Access Memory? That makes no sense... Should be RWM or something. But RAM is more catcy.

Ryan
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Old Apr 22, 2013, 06:13 PM
Registered User
Windsor, Canada, near Detroit
Joined Jul 2007
4,322 Posts
updrafts?

now it comes to my mind the term used by pilots when the plane suddenly sinks: they call it a downdraft.

why not then call the opposite 'updraft'?

it makes sense, sounds technical, and is easy to understand.
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Old Apr 22, 2013, 07:01 PM
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United States, OK, Moore
Joined Jan 2006
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The term "updraft" is frequently used, although to me, an updraft is more akin to an upward deflection of the wind (think slope soaring, or wave soaring) rather than a thermal.
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Old Apr 22, 2013, 09:24 PM
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another

Quote:
Originally Posted by LVsoaring View Post
The term "updraft" is frequently used, although to me, an updraft is more akin to an upward deflection of the wind (think slope soaring, or wave soaring) rather than a thermal.
got ya.

then let's try another 1.
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Old Apr 22, 2013, 09:31 PM
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USA, AZ, Tucson
Joined Apr 2002
514 Posts
I just call it "the good stuff"
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Old Apr 23, 2013, 12:01 AM
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United States, MA, Waltham
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Thermals are caused by thermal differences.

I've flown off a frozen lake at sunset and caught a thermal. In the winter, I've also flown the thermal generated by the furnace in my parent's house. I circled for 10 or 15 minutes and then the thermal stopped as if turned off by a switch. Which, of course, it was. Mom later commented that I'd been circling exactly over the house.
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Old Apr 23, 2013, 05:34 PM
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sawman's Avatar
Louisiana
Joined Oct 2005
1,176 Posts
To be precise, there is no such thing as "hot" or "cold". You have heat or the absense of heat. Heat is a form of energy. Cold is just a word people have become accustomed to using to describe the absence of heat.
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