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palmsOrl

Climate of Extreme South Florida Truly Tropical?

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stevethegator

I love this discussion! As a kid growing up in "SoFla" I always wanted to travel somewhere "tropical" so what does that tell you?

But, when I flew from Ft. Lauderdale to San Juan this past December I didn't notice a difference between the two places, in terms of temperature or vegetation (Puerto Rico being slightly more "green" due to higher rainfall, fertile volcanic soil). I really didn't notice a difference in the Islands either until I got to Dominica, which at 15N, is covered in solid tropical rainforest and has average daytime temps of 85 degrees year round.

Just my two cents: like they say its all about how you define it. Geographically South Florida is "subtropical" being between the Tropic of Cancer and 32N. Climactically (Koppen) it fits the definition of tropical, average temp above 64.4. But why 64.4 and not 65? Does it really matter? Doesn't change what the place actually is.

Personally I like to look at the native ecosystems of an area. South Florida has four distinct naturally occurring "tropical" ecosystems: tropical hardwood forests, mangrove estuaries, shallow water coral reefs, and tropical savannah (in the everglades). However, it also has temperate ecosystems as well: cypress swamp, pine flatwoods, and mixed deciduous forest. That's what makes South Florida so special, it has both temperate and tropical ecosystems right next to each other!

So, when I'm down there in a hammock surrounded by giant Ficus, gumbo limbo, black ironwood, mahogany, mastic, and all other manner of West Indian vegetation, coupled with the associated tropical animal life I really am somewhere tropical. But when I'm in a cypress swamp or some pine woods I'm somewhere temperate. And when I'm in the Fakahatchee strand and there are native Roystoneas growing right next to native red maple I don't know where I am! Haha

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Walt

While serving in the navy I spent the month of February in San Juan, Puerto Rico, (1969) and spent 13 months in Key West, Forida, (June 1970 to July 1971). During the winter months there is a discernible difference between the two in terms of both daily low and high temperatures. I recall many days while in Key West having to wear a dungaree jacket during some winter days when it was overcast and the wind was coming out of the northwest. I never had to wear a jacket in San Juan, even on the most overcast, coolest day. I've also been to Dominica, Martinique, and Barbados during the month of February, and all were very tropical indeed.

As far as the odd number of 64.4 degrees F, that's because it's converted from metric. 18 degrees Celsius = 64.4 Fahrenheit (18C x 1.80 = 32.4 + 32 = 64.4).

Still, 18C is just an arbitrary temperature reading. Personally, I think 64.4 degrees F for the average temperature for the coldest month of the year is a little on the low side. But I will accept that as being right on the margin of the tropics, and not representive of what I consider the true tropics.

As for the tropics lying between 23.5 degrees south and 23.5 degrees north, Midway Island lies slightly more than 28 degrees north (slightly farther north than Tampa, Florida) and it's lowest temperature ever officially recorded is 54 degrees (USDA zone 12), and 51 degrees unofficially.

http://home.comcast.net/~k7aty/MidwayIsland/List/About_Midway_Island.pdf

http://weatherspark.com/averages/33140/Sand-Island-Midway-Islands

http://www.palmtalk.org/forum/index.php?/topic/18760-midway-atoll-28-12-north/?hl=%2Bmidway %2Batoll

Edited by Walt
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displaced_floridian

That's an interesting definition, "...with diurnal variations in temperature exceeding seasonal variations." That would rule out Key West, where the absolute low is 41*F, and Bermuda, where the absolute low is 45, and Midway, where the absolute low is 54, even though ultra-tropical vegetation can grow in these areas. If the seasonal variation is too pronounced, it's not really tropical, which would seem to be more a function of latitude. Here are some interesting graphs...

post-4141-0-85540800-1391193865_thumb.jp

post-4141-0-09419900-1391193879_thumb.jp

post-4141-0-03999900-1391193891_thumb.jp

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stevethegator

I think the biggest misconception people have about the tropics is that it's all uniformly hot and steamy year round everywhere "tropical." That's certainly true in some places but not all. Even along the equator there are glaciers, deserts, and many other ecoregions beside tropical rainforest.

Lack of a freeze doesnt really say much on its own anyway, there are subantarcitc islands that are frost free but certainly aren't tropical. As has been pointed out, there are many places south of the Tropic of Cancer that have seen freezing temperatures at or near sea level (Tampico Mexico, Southern China, even northwest Cuba in the 1800s). And, there are places far ouside the actual tropics like Midway that are universally considered to be tropical.

I think when most people go to Miami they think "tropical", not only because of the weather but because of the landscaping, beaches, culture, and overall vibe of the place. Whereas if most people went to the pine forests of Nicaragua they wouldn't think "tropical" but they'd definitely be in a tropical location.

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Brahea Axel

This is turning into a strange thread. There's no such thing as "tropical" in a black and white sense, that is a gross generalization and no definition you come up with is going to work given that in the real world, geographical climate changes are very much gradual.

I would look at plant adaptations instead and use them as indicators. If you can grow breadfruit 365 days outdoors, your climate is tropical.

You could define a "semi-tropical" climate which Florida is often referred to. If you can grow breadfruit outside for the majority of the year, and you might get an occasional extreme, then your climate is probably "semi-tropical". But good luck defining the lower boundary.

But temperature is a poor definer for what is tropical. The intensity of the sunlight as a function of latitude and elevation are really the primary factors because they are the primary drivers for soil temperature.

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palmsOrl

Despite rare arctic invasions (which are known to affect other tropical areas such as Cuba, N Australia, etc.), the average temperature of the coldest month in Key West is 70F. That most certainly meets my definition of tropical. As with other climate zones, there are all degrees of tropical, from marginal areas like the southern tip of FL to the equatorial tropics of lowland Brazil. Key West is simply a tropical area with lower average winter temperatures (and extremes) than San Juan. The vegetation is virtually 100% tropical in Key West and must be ~90% tropical in Miami. There is not a doubt in my mind that South Beach is a tropical location.

What you get to see in FL is the mixing of temperate and tropical as Steve mentioned. There used to be a huge birch on a canal near me covered in a tropical aroid vine. Scenes like these are common in Central Florida.

Steve, what you may have noticed as you worked your way south through the Lesser Antilles and arrived in Dominica is the beginning of the equatorial tropics. A great majority of the landmass between 15N and 15S latitude is (or was :violin: ) covered by tropical rain forest.

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tropicbreeze

"Despite rare arctic invasions (which are known to affect other tropical areas such as Cuba, N Australia, etc.)..."

Where on earth did you gather that "fact" from, a Disney comic book? Apparently the breadfruit here is an "arctic invasion" resistant variety, LOL.

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palmsOrl

FLTropicalZone.gif

This is a map I came up with a few months ago around the time I first posted this thread. This map depicts in green, areas with January average temperatures of 64F or higher. I drew demarcation line to distinguish tropical and subtropical and had to guesstimate a bit in the Everglades since there are few weather stations in the interior. You will note, that technically Sanibel Island meets the technical definition of tropical, whereas Pine Island does not (quite). The zone extends to just a bit north of Stuart on the East Coast.

I feel the Koppen definition of tropical is actually pretty good as this map closely reflects the tropical (predominently)vegetation zone in Florida. Tropical vegetation (even native) does sneak a good bit further north on both coasts, since low temp extremes are moderated in these areas, while average temperatures fall below tropical criteria. Examples are places such as St Petersburg, Merritt Island and Vero Beach.

I guess if you really wanted to get technical and say the cutoff is 64.4F, I could just lower the cutoff line on the map, say 20 miles all the way along and call it a day. :winkie:

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palmsOrl

"Despite rare arctic invasions (which are known to affect other tropical areas such as Cuba, N Australia, etc.)..."

Where on earth did you gather that "fact" from, a Disney comic book? Apparently the breadfruit here is an "arctic invasion" resistant variety, LOL.

Okay, I should have send Antarctic invasion, or I could just say polar. I didn't say all areas of Northern Australia experienced antarctic invasions of cold. But accounts of cold and even freezing weather well into far Northern Queensland (into tropical areas) exist here on Palmtalk from a few years ago.

Axel, I agree with you in general. I am referring to the Koppen definition specifically which seems to be a pretty good predictor of tropical vegetation dominance. It is not perfect though.

The breadfruit is renowned as a particularly cold sensitive tree (like Cyrtostachys and Manicaria, extremely cold sensitive palms). This sensitivity does not mean Cocos, Ptychosperma, Mango, etc. are not tropical.

Edited by palmsOrl

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tropicbreeze

It all gets back to how you define tropical, and on that of course you'll never get concensus. Years ago I met some girls from the US in Paris. It was winter and they insisted Paris was subtropical. On internet forums there's lots of differing views. People in zone 9 in Florida claiming they're tropical. A US city information site claiming they were tropical because on average they only have 2 snow events per year. A few years ago I had some people I knew from Tampa Florida visit. It was just starting winter and they thought we were having a summer heat wave. People are an unreliable judge of climate, and they will believe what they want to believe.

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amazondk

Ultratropical or Equatorial is even more strict that this, possibly an average minimum temperature of 60. Places like singapore, lowland Costa Rica, Equaltorial Brasil (as was mentioned above) and others clearly fit this criteria. I believe the record low in Singapore is 67F. Well-deserving of the ultra prefix!

I have lived in Manaus since 2000 and have been here frequently since 1989. I can not remember ever seeing a nightime temprerature lower than 70 F.

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stevethegator

FLTropicalZone.gif

This is a map I came up with a few months ago around the time I first posted this thread. This map depicts in green, areas with January average temperatures of 64F or higher. I drew demarcation line to distinguish tropical and subtropical and had to guesstimate a bit in the Everglades since there are few weather stations in the interior. You will note, that technically Sanibel Island meets the technical definition of tropical, whereas Pine Island does not (quite). The zone extends to just a bit north of Stuart on the East Coast.

I feel the Koppen definition of tropical is actually pretty good as this map closely reflects the tropical (predominently)vegetation zone in Florida. Tropical vegetation (even native) does sneak a good bit further north on both coasts, since low temp extremes are moderated in these areas, while average temperatures fall below tropical criteria. Examples are places such as St Petersburg, Merritt Island and Vero Beach.

I guess if you really wanted to get technical and say the cutoff is 64.4F, I could just lower the cutoff line on the map, say 20 miles all the way along and call it a day. :winkie:

I think this is pretty good too. I went to undergrad at UF and when I'd drive home to visit my family you would definitely notice a difference when you got south of Ocala (more "subtropical" with syagrus, pheonix, etc. starting to appear widely and temperate hardwood species becoming less abundant), and then a much more sudden difference once you got to the Stuart area.

Like you said, that southern "tropical" line also corresponds nicely with the native distribution of tropical hardwoods and most epiphytic orchids, as well as the ability to reliably grow Cocos.

Maybe Koppen was on to something after all with his "random" choice of 64.4F (18C, the 64.4 makes a lot more sense now Walt pointed that out! I'm not that dumb I swear)

Edited by stevethegator

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Brahea Axel

FLTropicalZone.gif

This is a map I came up with a few months ago around the time I first posted this thread. This map depicts in green, areas with January average temperatures of 64F or higher. I drew demarcation line to distinguish tropical and subtropical and had to guesstimate a bit in the Everglades since there are few weather stations in the interior. You will note, that technically Sanibel Island meets the technical definition of tropical, whereas Pine Island does not (quite). The zone extends to just a bit north of Stuart on the East Coast.

I feel the Koppen definition of tropical is actually pretty good as this map closely reflects the tropical (predominently)vegetation zone in Florida. Tropical vegetation (even native) does sneak a good bit further north on both coasts, since low temp extremes are moderated in these areas, while average temperatures fall below tropical criteria. Examples are places such as St Petersburg, Merritt Island and Vero Beach.

I guess if you really wanted to get technical and say the cutoff is 64.4F, I could just lower the cutoff line on the map, say 20 miles all the way along and call it a day. :winkie:

This looks pretty darn good to me! I wouldn't sweat it on 64F or 64.4F, that's the problem you face with this anyway, it's the lower boundary that is so fluid. It should be 64F +/- 1F at least so make the boundary fuzzy and no one can argue with it.

I've always known that there is a magical line somewhere between 15C and 20C when it comes to overnight lows and tropical plants. That's why in Southern California they can grow many marginal palms and tropical fruit trees that I cannot. My overnight lows in the Summer are below 55F, and it has a huge impact on the range of plants I can grow. Overnight Summer lows in many parts of Southern California are routinely over 64F and that makes all the difference in the world.

I like to use the overnight lows as a means of defining tropical versus subtropical versus mediterranean.

tropical: plants stop growing below 59F/15C (For ex: breadfruit, coconuts, cacao)

sub-tropical: plants stop growing below 45F/7C (For ex: many pinanga species, some dypsis, etc...)

highland tropical: plants grow relatively actively all the way down to just above freezing 32F/0C (for ex: parajubaea, ceroxylon, rhopies, howea)

Then the other two dimensions to take into account is dormancy and hardiness. Some plants have dormancy capacity, some don't. Breadfruit can't go dormant, it just dies below about 50F. But a coconut can handle hanging out below it's comfort zone for very short periods of time, apparently quite a bit if you consider the Newport coconut. A lot of drought tolerant tropicals can handle long periods of dormancy when roots can't supply nutrients. Hardiness is the last limiting factor, it determines the rest.

I can use examples for all of these. Mountain papayas and Dictyocaryum lamarkium grow right down to freezing, but have no hardiness, and will croak below 32F. In contrast, tropical papayas stop growing below 59F and croak below 45F. breadfruit literally freezes below about 52F. On the other extreme, Arenga engleri stops growing below 59F but has an incredible capacity for dormancy and for hardiness. Hence it will grow in San Francisco but only put on one leaf a year. A lot of dypsis have phenomenal dormancy capabilities. Dypsis robusta stops growing below 59F but has a large capacity for dormancy.

It all gets back to how you define tropical, and on that of course you'll never get concensus. Years ago I met some girls from the US in Paris. It was winter and they insisted Paris was subtropical. On internet forums there's lots of differing views. People in zone 9 in Florida claiming they're tropical. A US city information site claiming they were tropical because on average they only have 2 snow events per year. A few years ago I had some people I knew from Tampa Florida visit. It was just starting winter and they thought we were having a summer heat wave. People are an unreliable judge of climate, and they will believe what they want to believe.

You're looking for consensus from the average Joe on the street on climate topics? This isn't politics, this is science.

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JEFF IN MODESTO

Axel, What was your Jan average temp. Jan 2014?

I know Burbank, Ca this year was pretty darn close to the magical 64.0f Jan mean.

Might I add that for someplace to be tropical, it also must be usda zone 11.

Cant have just warm averages....There has to be an absence of any regular freezing.

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amazondk

The one thing that I know is defined as tropical is where I live. I come and go to Florida on a relatively frequent schedule. Sometimes when I walk out the door at MIA it is even hotter than when I left Manaus. And, other times there is a cool breeze. There is never a cool breeze here. That is unless one is on the river in a rain storm in a fast boat.

Manaustemps_zpsd1673d1e.jpeg

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stevethegator

The one thing that I know is defined as tropical is where I live. I come and go to Florida on a relatively frequent schedule. Sometimes when I walk out the door at MIA it is even hotter than when I left Manaus. And, other times there is a cool breeze. There is never a cool breeze here. That is unless one is on the river in a rain storm in a fast boat.

Manaustemps_zpsd1673d1e.jpeg

Now that's tropical! Interesting that the daytime averages rise a bit in the fall but the lower averages stay the same. Is fall the drier season?

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amazondk

Steve,

Your observation is right. The dry season is what is called the Amazonian summer. The wet season the winter. Since the sun is pretty much the same angle overhead all year cloud cover plays an important role in temperture. So, even though we are in the southern hemisphere the season really has nothing to do with the real southern hemisphere summer which is in the rainy season of equatorial amazonia. March is normally the month with the most rain, which is reflected in the graph. I think that the graph does reflect temperature readings taken in the area of the Manaus urban heat island effect. The temperatures at night away from the city normally are a few degrees lower. The other place where it can one feels very uncomfortable and actually cold is in the rain forest during the rainy season. I do not think that the temperature actually drops much, it is just so gloomy and wet that for some reason it is easy to feel chilled. When it decides to rain it can really rain around here. I guess that makes sense since it is a rain forest.

dk

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palmsOrl

Tropical is a spectrum all the way from the most consistent year round tropical of Manaus or Singapore to the marginal tropical of Miami or the Northern Bahamas. Just like Sarasota, Atlanta and Washington DC are all humid subtropical climates, according to the Koppen definition. There is quite a variation within a given climatic designation.

Southern California has some USDA zone 11 micro climates in the foothills, but nowhere in the state is it tropical.

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Brahea Axel

Axel, What was your Jan average temp. Jan 2014?

I know Burbank, Ca this year was pretty darn close to the magical 64.0f Jan mean.

Might I add that for someplace to be tropical, it also must be usda zone 11.

Cant have just warm averages....There has to be an absence of any regular freezing.

80F+50F/2 = 65F, and that was a good day. Bad day was 75F+44F/2 = 60F. the last 6 weeks ranged anywhere from 60F to 65F, but I guarantee it was anything BUT tropical. Days too short and the high only for a few hours. Highland tropical maybe, but even then the sun angle is too low to really properly warm up the soil.

Right now, try 60F+40F/2 = 50F, definitely NOT tropical right now. :) All this warm weather made me soft, hopefully my plants didn't get too soft either.

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Walt

I don't profess to know much about the tropics and all the variances in tropical climates. I only have a basic knowledge, knowing the tropics consist of tropical rainy and tropical dry, with some subclimates, such as rainforest, monsoon rainforest, and tropical savannah (and variances among these).

If I lived in the tropics, I would prefer not to live in a wet, humid, oppressive climate,where when you sweat there would be little if any evaporative cooling. I think I would prefer a distinct rainy season, but a dry season with enough rain to keep flora green and lush.

I remember the first time (while in the navy) my ship went to Guantanamo, Cuba. I was surprised to find the landscape to be a dry, scrub cacti. Yes, there were coconut palms and others, but by no means was the landscape rich and lush. But I'm sure all of Cuba isn't like Guantanamo.

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_Keith

No. You could ask David Fairchild if he was alive. He would say no.

In 1989, nothing died in the tropics. You could ask Ken Johnson about 1989, he is alive.

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stevethegator

Steve,

Your observation is right. The dry season is what is called the Amazonian summer. The wet season the winter. Since the sun is pretty much the same angle overhead all year cloud cover plays an important role in temperture. So, even though we are in the southern hemisphere the season really has nothing to do with the real southern hemisphere summer which is in the rainy season of equatorial amazonia. March is normally the month with the most rain, which is reflected in the graph. I think that the graph does reflect temperature readings taken in the area of the Manaus urban heat island effect. The temperatures at night away from the city normally are a few degrees lower. The other place where it can one feels very uncomfortable and actually cold is in the rain forest during the rainy season. I do not think that the temperature actually drops much, it is just so gloomy and wet that for some reason it is easy to feel chilled. When it decides to rain it can really rain around here. I guess that makes sense since it is a rain forest.

dk

That's fascinating. I've always been interested in Amazonia, it seems like a special place. One thing I have to ask, how are the biting insects?

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stevethegator

No. You could ask David Fairchild if he was alive. He would say no.

In 1989, nothing died in the tropics. You could ask Ken Johnson about 1989, he is alive.

True, and that's certainly not something you see very often in tropical locales. But, for argument's sake I'm sure ALOT of stuff died in Tampico when it was 27 and failed to get above 40 for days, and when it was 33 (there are unconfirmed reports of way colder, even snow) in Western Cuba, and when it freezes quite regularly in Southern China. But all of those places still have tropical climates and are even technically "in the tropics" because they lie south of the Tropic of Cancer.

I think "tropical" is near impossible to define. In terms of latitude South Florida isn't tropical, it's not in the tropics. But neither is Midway and the record low is 54F there. The converse is also true, are Tampico and Southern China not tropical even though they're in the tropics and classify as having tropical climates by averages, just because it's frozen there before? Not trying to start trouble, I just find it an interesting dilemma

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amazondk

Steve,

Your observation is right. The dry season is what is called the Amazonian summer. The wet season the winter. Since the sun is pretty much the same angle overhead all year cloud cover plays an important role in temperture. So, even though we are in the southern hemisphere the season really has nothing to do with the real southern hemisphere summer which is in the rainy season of equatorial amazonia. March is normally the month with the most rain, which is reflected in the graph. I think that the graph does reflect temperature readings taken in the area of the Manaus urban heat island effect. The temperatures at night away from the city normally are a few degrees lower. The other place where it can one feels very uncomfortable and actually cold is in the rain forest during the rainy season. I do not think that the temperature actually drops much, it is just so gloomy and wet that for some reason it is easy to feel chilled. When it decides to rain it can really rain around here. I guess that makes sense since it is a rain forest.

dk

That's fascinating. I've always been interested in Amazonia, it seems like a special place. One thing I have to ask, how are the biting insects?

Regarding biting insects the worst ones are ants. You have to be real careful where you walk in the forest. As to flying insects in the Negro River area there are some, but much less than most parts of Florida. There are very few mosquitoes in many places, especially along black water rivers. There are some annoying little flies at some times of the year. And, on the muddy water rivers, like the Amazon there are a lot of mosquitoes at night, but not many in the daytime. That being said you can get malaria and denque fever which are endemic to the region. It only takes one to infect you. The mosquito which transmits dengue is known as a domestic mosquito as they live close to humans,often in your home. Whereas the malaria mosquito lives in the bush. Amazonia is a special place, hard to describe,

dk

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amazondk

I

If I lived in the tropics, I would prefer not to live in a wet, humid, oppressive climate,where when you sweat there would be little if any evaporative cooling. I think I would prefer a distinct rainy season, but a dry season with enough rain to keep flora green and lush.

Walt,

The summer in South Florida is every bit as humid as here in the equatorial humid tropics. The nights in the summer in S. Florida are even worse than here. The big difference is the winter. There is no real winter here as the graph I posted shows. But, the rainy season, although more humid than the dry season is more comfortable as the temperature does not get as high. The peak of the dry season has the lowest humidity which in the daytime ranges around 50 percent, unless it rains. And, AC has made a big difference in life here as it has everywhere. One of the things in my specific location is a lack of wind for the most part. There is a breeze by the rivers. But, the kind of breezes and winds found in locations with the trade winds does not exist.

One thing that is either cultural, or maybe even physical is that Brazilians tend to have a higher heat tolerance than Americans.

dk

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Walt

I

If I lived in the tropics, I would prefer not to live in a wet, humid, oppressive climate,where when you sweat there would be little if any evaporative cooling. I think I would prefer a distinct rainy season, but a dry season with enough rain to keep flora green and lush.

Walt,

The summer in South Florida is every bit as humid as here in the equatorial humid tropics. The nights in the summer in S. Florida are even worse than here. The big difference is the winter. There is no real winter here as the graph I posted shows. But, the rainy season, although more humid than the dry season is more comfortable as the temperature does not get as high. The peak of the dry season has the lowest humidity which in the daytime ranges around 50 percent, unless it rains. And, AC has made a big difference in life here as it has everywhere. One of the things in my specific location is a lack of wind for the most part. There is a breeze by the rivers. But, the kind of breezes and winds found in locations with the trade winds does not exist.

One thing that is either cultural, or maybe even physical is that Brazilians tend to have a higher heat tolerance than Americans.

dk

No doubt, it's a subjective preference as to the best place in the tropics (all other things considered aside from weather) to live, if one wanted to live there. Every where there are trade offs of one thing or another. Myself, I would like a marked change of seasons, but average low temperatures during the winter months to not go below 50F(10C), and only that low on the coldest few days of the winter. I would just want some kind of break from the long summer heat and humidity. But summers here in Lake Placid, Florida, can get fairly brutal, more so than Miami, at least during the day, as I'm not in proximity to water. As such, nighttime lows can get cooler as there's no hot body of water to hold nighttime temperatures up. On my same latitude over on the Gulf of Mexico side, nighttime lows during peak summer months can sometimes be terrible. I've seen low over there not getting below 85 degrees (29+C) or slightly higher.

You are right about air conditioning. In the summer months I get what I need to get done outside by 10 a.m., then head for either shade work (back in my wooded areas where I have lots of tropical plantings) or in the house. I will re emerge in the evening when the sun is at a much lower angle.

Being on the the equator, where the days are the same length year round (I understand your are at 3 degrees, so there would be a slight variance), places like Miami could even be more tropical (as per definition) during the the summer soltice, where the days are about 1-1/2 hours longer than at the equator (more hours to absorb short wave radiation from the sun).

I understand twilight is a much faster event right on the equator than at high latitudes. They also say that nighttime is the winter in the tropics (i.e., only time the temperature would signifigantly drop).

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Jimbean

This is my 2 cents:

post-664-0-05598200-1391728580_thumb.gif

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Jimbean

In my opinion, zones 11 and above are tropical, 9 and 10 subtropical, and 7 and 8 warm temperate.

Florida has zones 11B to 8B

Edited by Jimbean
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stevethegator

The only problem with the USDA zones is that they only look at average minimums, so a place that was constantly 40 degrees year round would be zone 11!

Also, from what a I understand there are pockets of zone 11 in Southern California, and yet fewer tropical plants grow there than in 10a South Florida due to lack of heat (cocos and adonidia are common palm examples of this).

This is why I think Koppen works best. Not a perfect system by any means (Philly and Tampa both the same "humid subtropical"?) but does a good job following natural vegetation patterns (Tampa and Philly both have temperate deciduous forest) and differentiating between places like Southern Cal and South Florida by comparing overall temperature/precipitation averages

Edited by stevethegator

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Jimbean

I don't do zones based on average annual minimums, I do them based on what grows where long term. Since the principle interest is where tropical plants can grow long term, I posted my map.

Edited by Jimbean
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stevethegator

I think your map is correct, there's definitely a strip of warmth along both costs and even some zone 11 on mainland coastal locations which the map shows!

I never really thought about it until I looked at the 11B on your map but I imagine the Marquesas Keys and the Dry Tortugas are even warmer than Key West (maybe even Havana) as they're surrounded by some large expanses of fairly deep water. Too bad they're (basically) uninhabited and so salty, I wonder if they are warm enough to support breadfruit, crytostachys, etc.

Edited by stevethegator

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Xerarch

Interestingly enough, on the new interactive USDA zone map, Key West is warmer than the Dry Tortugas and about the same but slightly warmer than Marquesas. Dry Tortugas actually shows up as zone 11a which is interesting given that it is more isolated. The map isn't perfect so I don't know how accurate that is, but interesting anyway.

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stevethegator

Urban heat island maybe? Or, like you said data accuracy could be an issue, those islands are remote.

On the other hand the Tortugas have been used by the government for a long time with the fort and such so you'd think there'd be a good weather station out there.

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Jimbean

Interestingly enough, on the new interactive USDA zone map, Key West is warmer than the Dry Tortugas and about the same but slightly warmer than Marquesas. Dry Tortugas actually shows up as zone 11a which is interesting given that it is more isolated. The map isn't perfect so I don't know how accurate that is, but interesting anyway.

Interestingly enough, on the new interactive USDA zone map, Key West is warmer than the Dry Tortugas and about the same but slightly warmer than Marquesas. Dry Tortugas actually shows up as zone 11a which is interesting given that it is more isolated. The map isn't perfect so I don't know how accurate that is, but interesting anyway.

That is an error on the new map.

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Jimbean

I also want to state for the record, I made that map back in 2009, and it shows some similarities with the 2012 USDA map.

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Jimbean

Blue/green is 8B

orange is 9A

Yellow is 9B

red is 10A

brown is 10B

Light brown 11A

Dry Tortugas 11B

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palmsOrl

This is my 2 cents:

I would say this map is much closer to reality than the 1990 map. I especially agree with the pattern of zone 10a up the coasts of Central FL. I think there should be a bit more 10a in some of Central FL. Much of even rural E. Central FL from Orlando south is 9b. This area in general does not average an annual lowest temp below 25F, except a few cold microclimates. Metro Orlando is 10a as I'll bet data from the last 25 years at the Executive Airport near downtown would indicate. Also, I would speculate that Gainesville and Ocala do not qualify as 8b with the last couple decades of data included. Maybe as of 1990, but not now. Tallahassee does, but not by that much.

I would say Key West and Dry Tortugas are at least as warm as Havana. The lowest Key West has officially recorded is 41F, whereas Havana hit 39F in 2010. I have no doubt the barrier islands of Miami are zone 11a on average, as Steve suggested.

Your biggest limiting factor to Cyrtostachys and breadfruit in the lower Keys is adequate irrigation and perhaps salt exposure.

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Walt

This is my 2 cents:

Overall, the map looks accurate to me. With respect to my area in Highlands County along the Lake Wales Ridge, the higher ground (reflected in the yellow 9b color) of the ridge does in fact provide a 1/2 USDA zone higher that those nearby adjacent areas down off the ridge. In fact, I dare say many areas are even zone 10a. I know in the town of Lake Placid it's zone 10a. After 16+ years of living just outside of town in zone 9b, I can state empirically the town is zone 10a -- plants don't lie. The below two coconut palms have been growing up in town for at least 12 years (first time I saw them). You don't get coconut palms like these in zone 9b.

Almost 100 percent of the coldest temperatures we get here are from radiational cooling events, not advective. As such, the air is stratified and much warmer at the higher elevations on the ridge, than down off it. When our local radio station meteoroligist gives a forecast, he typically will say, the low's tonight will range from 30 degrees low ground, 37 degrees high ground. I've confirmed this in the wee morning hours by driving my car from down off the ridge to up on the ridge, and watch my car thermometer rise 6-7 degrees within the one minute to drive up the grade.

TwoLakePlacidcoconutpalms_zpsd5470806.jp

The above palms are growing on Lake Pearl Drive in Lake Placid, one block north of Lake Pearl. I have photos of these palms in 2002 when they were much smaller. They did get some damage in 2010, but I think that was more from cold duration than absolute low temperature.

The below coconut palms are growing in Sebring, Florida, and on relatively high ground. These palms have been there 6-7 years (when I first saw them). I believe this area to be zone 10a. These palms were hurt in 2010 but recovered quickly.

CoconutpalmsSebringFlorida_zpseac7518a.j

Also, I submit that around most of all of the lakes here is a solid zone10, with it being slightly warmer on the southeast sides. I have a buddy who lives on Lake June (about five miles from me) and so far this winter his low has been 41 degrees, whereas my low has been 30 degrees (both on the same day). We've been comparing low temperatures for the last 6-7 years. My buddy's lakefront neighborhood is loaded with fruiting coconut palms. This is an impossibility in my non lakefront neighborhood.

Below are some coconut palms growing on the north shore of Lake Pearl, located on the south edge of the town of Lake Placid. The resident that owns these palms is a local landscaper. He had them planted a few years ago.

CoconutpalmsonnorthshoreofLakePearle_zps

Below is a coconut palm growing about 300 feet from the east shore of Lake Grassy, just south of the town of Lake Placid. This lakefront community is loaded with coconut palms, indicating it's a zone 10+ area.

CocosnuciferaLakeHuntleyLakePlacid_zpsd3

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Jimbean

I actually already have Lack Placid as a large 10A micro-climate. If you look closely, you will see a little red dot there.

I have driven all over central and south Florida, and the Lake Placid area is one of the more interesting places with regards to microclimates. From my observations, and taken into account some of the principles of cold air infiltration and topography, the central/south highlands county is sectioned in 10A, 9B, 9A, and 8B zones- all within about a 15 mile radius.

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Walt

I actually already have Lack Placid as a large 10A micro-climate. If you look closely, you will see a little red dot there.

I have driven all over central and south Florida, and the Lake Placid area is one of the more interesting places with regards to microclimates. From my observations, and taken into account some of the principles of cold air infiltration and topography, the central/south highlands county is sectioned in 10A, 9B, 9A, and 8B zones- all within about a 15 mile radius.

Yes, I saw that red dot and meant to ask you about it. If you ever come through Lake Placid again, check out Sun 'N' Lakes subdivision in Lake Placid. It's on the east side of Lake Grassy. I think that's about the warmest subdivision in Highlands County. I've driven up ever street and there's all kinds of tropicals. In December of 2012 I was riding around and noted two large royal palms in a resident's front yard, and could see the tops of coconut palms behind their house. A lady (formally from Cuba) was doing yard work, so I stopped my truck and asked her about the royal palms. She was delighted to talk, and even had her husband (also from Cuba) come out. They had three mature coconut palms in their back yard by the canal leading to Lake Grassy. They told me they had moved up here from Miami about 17 years before and planted the palms from small palms they brought up. The husband told me there coconuts weren't even hurt during the winter of 2010.

And you are correct about such a broad range of low temperature areas. I know first hand. Back in December of 2010 I had a low of 20.8 degrees. Archbold had 15 degrees (their all-time low is 13 degrees on two ocassions.). I was checking FAWN, Weatherunderground stations, and friend's weather stations, and there was a spread of more than 20 degrees in low temperatures spread across the county. I've seen as much as a 22 degree spread from Archbold's site to on lake locations.

During the winter of 2005-2006 I put a Halsey-Taylor hi-lo thermometer on a vacant lot at the base (on the ground) of a bay tree about fifty feet away from the Lake June shore. Lake June is 4,503 acres in area. As such, it has a notable effect on nighttime low temperatures in proximity of it. I went over to check my thermometer on the first major freeze. I don't remember now what the reading was, but I reset the thermomter. Then, on February 14, 2006, it got down to 27 degrees at my place. I drove over to the lake to check my thermometer and it read 42 degrees! My buddy that lives about 1/4 up the street, and across the street from the lake recorded 41 degrees. His neighbor (whom I'm also friends with) lives on the lake, and he said his thermometer down at his boat house read 43 degrees!

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