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Victoria, BC is an odd case when it comes to Koeppen vs. Trewartha classification.
In Koeppen, it's solidly in the Csb climate classification with only 607mm of precip a year which is drier than many classicial mediterranean cities (Rome, Nice, Dubrovnik) ... and almost 8 times as much precip in its wettest month compared to driest month.
However, according to Trewartha, it's solidly DO due to the temperature factor (not 8 months of temps of 10C or over).
The vegetation in Victoria is different enough from Vancouver to be distinctive. There are native stands of Arbutus trees and Garry Oaks which don't grow here natively (except for some isolated pockets in West Van in the case of Arbutus).
The landscape definitely looks drier there.
That vegetation doesn't look oceanic or humid subtropical at all (as you said, the vegetation changes from Cfb to Csb), and neither does the weather patterns. Lumping in dry-summer climates with oceanic or humid subtropical climates doesn't make any sense to me.
I'm not seeing what you see in the view, I'm seeing thick, lush, tall forest. A little bit more open than an East Coast forest, but has more in common in appearance with a humid forest than a typical Mediterranean forest getting say, 20 inches of rain / year.
The vegetation has a dry look and has more in common with classical Mediterranean forests in California than anything seen on the East Coast or coastal Washington. Is it a "humid" forest? Sure. But why should a place have to be practically semi-arid to be Mediterranean/dry-summer subtropical climate? Besides, from Cfb to Csb the vegetation changes to a more Mediterranean look, and although the higher annual precip is able to support more vegetation, the vegetation is still adapted to the dry season. East Coast plants would turn brownish with 1 month without rain (probably less), whereas the plants in this region wouldn't bat an eyebrow at 4 months without rain. Sometimes they can go for up to 5 or 6 months with no problem. The same dry season adaptation applies in places even farther within Trewartha's oceanic zone, such as Seattle. That combined with the vastly different weather patterns in Cfb vs. Csb leads to a very good case that lumping in Cfb and some Csb climates into the same oceanic zone is wrong.
Vegetation can withstand a true summer dry season much better if the rest of the year has higher precipitation. The West Coast of California can get very lush looking forests (think redwood forests) even though the summers are extremely dry. Midsummer in one of wetter coastal spots:
Forest type does change because of the dry summers, but it's very different from drier Mediterranean climates, which have more open forest and grassland. As the precipitation increases, the vegetation loses its stereotypical Mediterranean. I suppose for the basis of just classifying by weather patterns, Koppen's lack of precipitation limit makes sense. But if you care about vegetation type, Trewatha's might be reasonable in this case. Seemed like the same was true for the humid continental / subtropoical boundary for both types.
Quote:
Originally Posted by Patricius Maximus
That vegetation doesn't look oceanic or humid subtropical at all (as you said, the vegetation changes from Cfb to Csb), and neither does the weather patterns. Lumping in dry-summer climates with oceanic or humid subtropical climates doesn't make any sense to me.
It looks like it could be Oceanic vegetation to me, although I'm not sure if there is such a thing as typical Oceanic vegetation. I wouldn't say the forest in that photo looks dry either. I don't think having a campfire would be a problem.
Quote:
Originally Posted by deneb78
Victoria, BC is an odd case when it comes to Koeppen vs. Trewartha classification.
In Koeppen, it's solidly in the Csb climate classification with only 607mm of precip a year which is drier than many classicial mediterranean cities (Rome, Nice, Dubrovnik) ... and almost 8 times as much precip in its wettest month compared to driest month.
However, according to Trewartha, it's solidly DO due to the temperature factor (not 8 months of temps of 10C or over).
The vegetation in Victoria is different enough from Vancouver to be distinctive. There are native stands of Arbutus trees and Garry Oaks which don't grow here natively (except for some isolated pockets in West Van in the case of Arbutus).
The landscape definitely looks drier there.
1. Is there a precipitation limit for Cs (something like 890 or 900mm)?
How can this work as places like Naples, Italy exceed that and what else would they be besides Mediterranean?
Do the warm climates become subtropical and the cool ones become temperate? Was this a contributing factor for Trewartha classifying Portland and Seattle as temperate instead of Mediterranean?
2. Cs is winter dry, but does the dry season have to be determined using the driest summer month and the wettest winter month, or can the wettest month be in Autumn or Spring?
It makes sense that the dry season needs to be compared to the winter, so the climates with dry summers compared to Autumn or Spring are subtropical?
In answer to your question:
1) Trewartha sets a precipitation limit of 900mm, but Koeppen sets no limits. So Naples fails under Trewartha but passes under Koeppen. The same rationale probably explains why a PNW locations fail under Trewartha.
2) In a lot of Mediterranean climates the wettest month is actually in autumn or spring, but summers are typically and markedly drier. According to Koeppen the wettest month must be at least three times wetter than the driest month.
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