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Is 35 Degrees North and South Latitude The Geographic Subtropics?

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Is 35 degrees North and South latitude (to the tropics) the geographic subtropics? That it what I heard.

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On 28 April 2017 5:02:45 AM, PalmTreeDude said:

Is 35 degrees North and South latitude (to the tropics) the geographic subtropics? That it what I heard.

IMG_0270.JPG

It could maybe very loosely be defined along those lines, but if you took into account ocean currents and local circumstances the line wouldn't be exactly straight along the 35 degree lines. It would wander quite a few degrees either side of it.

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There's various definitions of subtropical.  One would be frost-free climate, but of course many higher-elevation tropical climates have frost or freezing weather.  Think of high mountains in Ecuador, Rwanda, Kenya, and New Guinea.

Closer to sea level, absence of frost gets pretty far north in coastal China and Taiwan, Burma, India, Iraq, Egypt, Libya, Atlantic Morocco, Sonora, and south in Chile (looks like almost 38ºS) and the Cape of Good Hope.  Most of Australia gets some frost.  

If you view "subtropical" as areas with frost in "some years only", then the Atlantic and Mediterranean coasts from Normandy onward  make it, including large, important areas of Portugal, southern Spain and much of Italy and Greece.  In the US, Pacific coast up to somewhere around the Columbia River.  Southern Hemisphere, more Chile, northern Argentina, coastal South Africa, most of Australia, Northland of New Zealand and much of the coastal North Island.  Source is an ancient, circa 1973, climate map from Oxford University Press.

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Posted (edited)

On 2017-6-2 01:54:43, Dave-Vero said:

There's various definitions of subtropical.  One would be frost-free climate, but of course many higher-elevation tropical climates have frost or freezing weather.  Think of high mountains in Ecuador, Rwanda, Kenya, and New Guinea.

Closer to sea level, absence of frost gets pretty far north in coastal China and Taiwan, Burma, India, Iraq, Egypt, Libya, Atlantic Morocco, Sonora, and south in Chile (looks like almost 38ºS) and the Cape of Good Hope.  Most of Australia gets some frost.  

If you view "subtropical" as areas with frost in "some years only", then the Atlantic and Mediterranean coasts from Normandy onward  make it, including large, important areas of Portugal, southern Spain and much of Italy and Greece.  In the US, Pacific coast up to somewhere around the Columbia River.  Southern Hemisphere, more Chile, northern Argentina, coastal South Africa, most of Australia, Northland of New Zealand and much of the coastal North Island.  Source is an ancient, circa 1973, climate map from Oxford University Press.

Actually in Spain you can also find areas with frost in some years only in the NW coast at 43ºN of latitude (A Coruña, very mild climate heavily influenced by the Atlantic Ocean) or even around Barcelona, which is at 41º20'N, which is protected from colder winds because it's between mountains and hills. The lowest temp in Barcelona since 1987 was barely -1.0ºC in the official station! https://en.wikipedia.org/wiki/Barcelona#Climate and it was just in one January.

Also other zones up to 39ºN in coastal central-east Spain see freezes just one time in many or dozens of years, last time since it was a light freeze here in the coast where I live, (38º40'N) was more than 20 years ago! Also Almería (SE Spain) is the only freezeless spot in mainland Europe looking at the official stations.

The island of Palma, Majorca, Spain at 39º35'N recorded just 2 times temps below 0.1ºC since 1981, one with 0.0ºC and the another -0.1ºC! (source)

Almería never went under 0.1ºC. I also think that a place like Almería or Alicante have completely subtropical climates, just as Palermo or Limassol.

Although the clearly northernmost winner with temps which never went under the freezing line is... Azores! As they're in the middle of the Atlantic Ocean!

Edited by Alicante
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I think depending on topography and distance from oceans, one could be "subtropical" at or further pole-ward of 35 degrees latitude. It also depends on how "subtropical" is defined, such as how cold it can get and for how long, how much heat one needs in the growing season, and how long the growing season is. And the plants used.

Merriam's Life Zones, though based on too short a period for too few weather stations, offer a clue to his thinking of "subtropical" for growing crops. He based his system on natural flora and fauna belts in North America, plus a formula of heat, cold, and accumulated heat in the growing season...another oops on his system is lessening the factor for winter. His Lower Sonoran in the dry west and Lower Austral in the humid east might be where "subtropical" meets "mid-latitude". 120+ years later of climate data and growing experience (including winter crop production), one might adjust his line to the south, so "subtropical" near its upper end includes Charleston SC, Savannah, Mobile, NOLA, Houston, Austin, Del Rio, and Presidio TX...then Tucson, Laughlin NV, and westward. Just my guess.

Others including geographers like Bailey might take where the daily mean temperature is above 32F (or warmer in wetter and cloudier climates?), and consider that the pole-ward boundary of "subtropical". That would include places like Albuquerque, Tulsa, Memphis, Atlanta, and Richmond in it. Or even north of those places in the east...not sure.

In 6th grade (1977) my class was taught 30 deg N / S and towards the equator was the start of subtropical, while 30 to 60 deg N / S was temperate or mid-latitude. That stuck with me. During a family spring break trip then, Montgomery AL (32N) was noticeably different than Mobile to New Orleans...weather and the advent of plant growth. 

Map-MerriamLifeZone_BirdMigration.jpeg

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Based on that old Oxford climate map, Galicia seemed like it might have climates similar to coastal Oregon, U.S.  Which leads me to wonder why Narcissus cyclamineus and N. bulbocodium don't seem to have gone wild in Oregon.  Of course there's a bunch of Oregon plants (including trees) that would likely thrive in Galicia.  

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The term subtropical is so ambiguous that it is nearly irrelevant. Koppen, with it's more relevant criteria and designations of particular climates, makes far more sense. I would suggest the Vero Beach that I am familiar with would likely come close to the criteria for the Koppen designation of Tropical ( i.e. average temperature Fahrenheit in coldest month equals 64.8 degrees). I was up there last month and coconuts and many other similar tropical plants were in abundance. 

The continuing promulgation of the meaningless USDA designations shows just how far out of touch with reality these bureaucracies are.  One need only to consider the example of a possible climate in the Pacific Northwest that may never freeze and therefore qualify for the coveted "USDA designation 11". However, the lack of heat would never allow this climate to grow the anticipated tropical plants afforded this designation( i.e. coconut et al). At the end of the day, is not the intended purpose of this beau racy (USDA) to create definitions that allow non-experts to have some idea of what their designated climate allows them to grow? If not, please tell me what purpose it serves.

As it relates to the term subtropical, logically it insinuates a temperate climate that may approximate tropical. Although numerous exceptions exist, I believe world-wide the 35 N to 35 S in large order can be accepted as an appropriate guide.

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Subtropical climates do not have to be frost free, most climatically defined subtropical regions get frost every winter.

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As Bubba noted, the Koeppen climate definitions remain widely used by climatologists in describing tropical climates.  Specifically, the average, or mean, temp of the coldest month must remain 18 degrees C or higher for the climate to be tropical.  So, logically, subtropical climates would have a coldest month with a lower mean temp.  But here in Hawaii, even though most lowland locations have coldest month mean temps in the low 70s, one still hears our climate described as subtropical.  I assume that is because we are relatively cool for a tropical location and humidity is tempered in many locations by the tradewinds.  Such a fluid definition, though.  I imagine some Florida, continental Asia, and other locations connected with temperate land masses must also have 18C or higher minimum monthly means, but vegetation cover may be restricted by quite cool or even freezing weather that arrives with some regularity.

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