Fascinating chart, Kevin - thanks for posting it. May I ask what publication this came from?
I will take the local’s old wive’s tale unless and until you have anything to back up your bald assertion. After you have felt a tremor or two in this neighborhood, it may be hard for somebody to understand the geology from your distance. Of course, it is not the only factor, but there is no reason to think that it is not a factor…
If Nebbiolo needs that much heat, how does that jive with G. Conterno’s theorem that Nebbiolo can handle cool and wet but not hot?
I think part of the answer is that people use terms like “cool” and “hot” in very different contexts. “Hot” for Pinot could be “cool” for Nebbiolo. That said, looking at the vintages of Barolo that I enjoy the most (2001, 2004, 2008, 2010), it does seem that a cool Fall is quite important. And summer can’t be too warm or the grapes ripen early and in the heat.
For example summer in 2010 was quite hot especially July but afterwards the weather was cooler than normal.
But why is there any reason to think it is a factor? Geothermal factors are not mentioned in any of the things on fog I found. If you’ve ever been in a farming area, or a forest, on a cool autumn or winter day when there was a mist rising from the earth, it’s pretty easy to see where the humidity is coming from.
I see you are an idiot. My apologies for assuming you were not.
If, as you assert, geothermal heat flux somehow caused fog, you would need to have a reason why. Let us assume your theory is that heat flowing up from the group somehow causes fog.
Fog can only occur when air is cooled, not heated, to its dewpoint. Accordingly, if, in imaginary world, geothermal heatflux was sufficient to materially warm the air over a large area (hint: it’s not), that would tend to reduce, not enhance, fog.
No doubt you are confused by images of licks of steam rising off of boiling volcanic lakes in Iceland, or steaming geysers in Yellowstone. That is, assuredly, not occuring in the Piedmont. If it were, you’d have, well, pillars of steam. Not fog. As you have in Yellowstone, a park that sits in a bowl surrounded by mountains and has some of the highest geothermal heat flux in the world. And does not have unusual amounts of fog relative to other high mountain valleys (though they do get fog in Yellowstone, and it is beautiful).
Or perhaps you were thinking of vog, like they have in the Big Island of Hawaii. Vog is not formed by geothermal activity, but from the emission of sulfurous gases and aerosols from a very active volcano. It is common in the Big Island of Hawaii. I would imagine that it rarely occurs near Etna. It does not occur in the Piedmont.
While I’m no expert in the climate of the Piedmont, given the geographic setting of the Piedmont I presume most of the persistent fog arises from radiation fog that gets trapped under an inversion in a bowl-like valley, much like Tule fog. The Piedmont is more subceptable to fog than other great wine regions because it is unusually humid for a mediterranean climate, and water vapor is a prerequisite for fog formation. It is also surrounded by mountains that can trap radiation fog.
Yes, very interesting and immediately generates questions about other grapes not shown there:
I imagine that Aglianico would be close Nebbiolo, but where exactly?
What about Barbera? Certainly to the left of Nebbiolo and the right of Pinot Noir - to the right of Dolcetto too?
Some quite interesting, but also quite irrelevant, gibberish. Did you knock yourself out on Wikipedia or something? (See if there is a Wiki article on thermal radiation and maybe you can get back on track.). And what sort of foolishness is “unusually humid for a Mediterranean climate”? Were you under the impression that St.-Tropez is arid? Are you too dense to understand the simple proposition that warm GROUND meeting cool AIR with the requisite moisture equals FOG, and that the warm and cool are NOT directional? More to the point, the ground need not be hot to the touch, David. We are talking a subtle phenomenon here. The heat is coming from somewhere in the late fall here, and the sun is not often the culprit on fog-bound, overcast days. Ever experience a cold front rolling off of the Alps, dropping the air temperature 20 degrees in its wake? Ever see what happens after cold rain hits hot pavement in the summertime? There is no inversion in a bowl-like valley here, no Yellowstone, no geysers and hot springs, and the volcanoes are well to the south, but instead, we have the rolling, substantial foothills of the Alps at some distance from the mountains themselves at most points. You had it right when you assumed that I was not an idiot. Thankfully, I did not assume that you were NOT a blowhard, so no need for any apologies on my part…
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B-. Would have been tempted to given you a C+ when I was a grad student teaching undergrad climatology, but you get a half point boost for originality.
I admit this conversation did send me to Wikipedia, and then to some other weather websites. From my extensive research over the past 10 minutes, it appears there are lots of ways fog can be created. Unfortunately, the amateur meteorologists hard at work to explain those ways here all seem to be missing the mark a bit – at least if Wikipedia and the National Oceanic and Atmospheric Aministration website can be believed: (1) cooling air is not the only way to create fog (sorry Keith), and (2) warm ground + cool air + moisture is not an exact recipe for fog either (sorry Bill). Interestingly, if you combine those two theories, you get something closer to the truth: radiation fog usually occurs when saturated soil, light winds, clear skies, and a small differential between temp and dewpoint coincide at night, with warm but cooling ground contributing both moisture and a drop in air temp – both of which push the air to close to 100% relative humidity. If there is no wind, you end up with dew or frost. If there is wind, its more likely you end up with fog.
Caveat: I did not know any of that until 10 minutes ago, when I became a weather geek for the first time in my life.
Huh? You need a refresher course in high school chemistry and physics, Bill. If the moisture in the warm air hadn’t already condensed, geothermally warm ground sure won’t make it do so!
Artist got a cloud to happen in a gallery:
Gilberto,
Since Barbera is often harvested after Dolcetto, I would guess is it would be to the right of Dolcetto and left of Nebbiolo (probably overlapping with both).
That’s fascinating, and makes sense from my anecdotal experience. I’ve been there in late June and late August, but not in between. (Also September, October and December.) Both summer visits it was pleasant but not hot.
Where is this from? And I’m curious how the ranges are calculated. Any idea?
What warm air, John?
You said the moisture in the air (of whatever temperature) would condense when it encountered the geothermally heated ground.
John,
The chart is from this paper - http://www.advid.pt/gestao2/An_overview%20_of_climate_change.pdf but I think it is a derivative as I have seen it used in other papers. My guess is that it is originally from another paper or a viticultural textbook.
FWIW, Back in the '40s a UC Davis professor named AJ Winkler characterized Nebbiolo as Region III or IV on his widely used Winkler Scale. Both are very warm. IMO he wasn’t far off, the Monforte data above is solidly Region III.
I dug around on Google and found that chart was created by Gregory Jones of Southern Oregon University - he’s a climatologist and is pretty well-known as a specialist on climate change and grapevines. Here’s a link to a paper he did that includes the same chart that Kevin posted:
http://academyofwinebusiness.com/wp-content/uploads/2010/05/Jones-G.pdf