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Kathryn

Tropical, Subtropical, Temperate and Frigid

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Kathryn

The following was summarized from information on the Wikipedia web site.

The tropics are the geographic region centered on the equator and limited in latitude by the Tropic of Cancer at approximately 23°30' N latitude and the Tropic of Capricorn at 23°30' S latitude. The word "tropics" comes from Greek tropos meaning "turn", because the apparent position of the Sun oscillates between the two tropics with a period that defines the average length of a year.

180px-World_map_tropical.png

In the Tropics, the sun is directly overhead at least once during the year - at the edges of the tropics this occurs at the summer solstice and over the equator at the equinoxes. This is the hottest part of the earth, and there are two annual seasons: a dry and a wet. This zone includes most of Africa, southern India, southern Asia, Indonesia, New Guinea, northern Australia, Central America and northern South America.

Tropical plants and animals are those species native to the tropics. Tropical is also sometimes used in a general sense for a tropical climate, a climate that is warm to hot and moist year-round, often with the sense of lush vegetation. However, there are places in the tropics that are anything but "tropical" in this sense, with even alpine tundra and snow-capped peaks, including Mauna Kea, Mt. Kilimanjaro, and the Andes as far south as the northernmost parts of Chile and Argentina. Places in the tropics which are drier with low humidity but extreme heat are such as the Sahara Desert and Central Africa and Northern Australian Outback.

The subtropics refers to the zones immediately north and south of the tropic zone. The term can be used loosely to mean a range of latitudes between 23.5 and approximately 40 degrees. These areas typically have hot summers-- even hotter than tropical climates. A subtropical climate implies that the air temperature usually does not go below freezing (0°C or 32°F). This is a threshold temperature for a gamut of plants, and applies to coastal California, Florida, northern India, most of eastern Australia, Texas, and coastal South Africa, for example. The poleward limit of such climates is higher on the west coasts of the northern continents and lower on the east coasts, because occasional Winter cold snaps reach farther south in the east. Some subtropical cities include New Delhi, Hong Kong, Athens, Curitiba, Cairo, Mexico City, Miami, Los Angeles, Houston, New Orleans, Brunswick, Georgia, Orlando, Tampa and Brisbane. Cities such as Darwin, Townsville and Cairns are not subtropical, and have truly tropical climates.

In certain areas of the world the subtropics are plagued by hurricanes, typhoons or tropical cyclones that originate in the tropics in the summer and fall. Subtropical locations don't usually have distinctly wet or dry seasons, and have a fairly even distribution of rain throughout the year.

At latitudes closer to the poles, the subtropical climate gives way to a "temperate" climate, characterized by annual mean temperatures of less than 20°C or 68°F and warmest month average temperatures of over 10°C or 50°F.

World_map_temperate.png

In the two Temperate Zones, the sun is never directly overhead, and the climate is mild, generally ranging from warm to cool. The changes in these regions between summer and winter are generally subtle, warm or cool, rather than extreme, burning hot or freezing cold. However, a temperate climate can have very unpredictable weather. One day it may be sunny, the next it may be raining, and after that it may be cloudy. These erratic weather patterns occur in summer as well as winter.

The north temperate zone extends from the Tropic of Cancer at about 23.5 degrees north latitude to the Arctic Circle at about 66.5 degrees north latitude and includes Great Britain, Europe, northern Asia and North America. The south temperate zone extends from the Tropic of Capricorn at about 23.5 degrees south latitude to the Antarctic Circle at about 66.5 degrees south latitude and includes southern Australia, New Zealand and southern South America.

Within these borders there are many individual climate types, which are generally grouped into two categories: continental and maritime.

The maritime climate is clearly affected by the oceans, which help to sustain somewhat stable temperatures throughout the year. In the temperate zones, the prevailing winds are from the west, the western edge of temperate continents most commonly experience this maritime climate. Such regions include Western Europe, especially the UK, and western North America at latitudes between 40° and 60° north (65°N in Europe).

The continental climate is usually situated inland, with warmer summers and colder winters. The large land mass increases its effects on heat reception and loss. In North America, the Rocky Mountains act as a climate barrier to the maritime air blowing from the west, creating a continental climate to the east. In Europe, the maritime climate is able to stabilize temperatures further inland, because the major mountain range - the Alps - is oriented east-west.

The two Frigid Zones, or polar regions, experience the midnight sun and the polar night for part of the year - the edge of the zone experiences one day at the solstice when the sun doesn't rise or set for 24 hours, while in the centre of the zone (the pole), this occurs all year round. The Frigid Zones are the coldest parts of the earth, and are covered with ice and snow. The North Frigid Zone (the Arctic) includes Greenland, northern Scandinavia, northern Russia, and the Arctic ice. The South Frigid Zone (The Antarctic) is filled by the continent of Antarctica; the next closest mainland is the southern tip of Chile and Argentina.

World_map_frigid.png

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John Case

Kathryn,

Thanks for the information that you provided regarding the definitions.

But......(there always is a but, of course) there are so many things that are particular to local climates (weather is daily, climate is a longer period, IMHO).

For example, the impact of the Japan Current in the Pacific and the Gulf Stream in the Atlantic can have major impacts on local weather with minor changes.

The Rocky Mountains are not the only contintental barrier in the US. From West to East, we have the coastal range, the Sierra Nevada, the Wasatch (check my spelling) in Utah before the Rockies appar. Each of these present changes to the environmental to the east of them.

There are a lot of other impacts as well. Each of us must deal with the local conditions. While technically I live in the San Francisco Bay Area, I can also say that I live in the East Bay and in the Sacramento Delta area. Each of these environments seem to pop up their heads on occasion. I can be from day to day, temperate, sub-tropical, and on occasion, very tropical when we get on the rare occasion high humidity with moderate temps.....

The definitions are helpful but everyone needs to monitor the weather aberrant conditions such as we had in California this January.

Thanks again,

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Kathryn

According to the Wikipedia information, New Orleans is considered subtropical.

The winter temperature doesn’t normally go below 30°F (-1°C), but sometimes drops into the low 20’s (-5°C). I think the last time we got down to 22°F was in January 2002. Since then we haven’t gotten below 28°F (-2°C) and this winter we got down to 30 or 32°F about five nights throughout the winter.

Lake Pontchartrain borders the north of the New Orleans area and gives us a warming effect. The lake is about 40 miles (65 km) across from east to west and about 25 miles (40 km) north to south – and only about 15 ft (5 m) at the deepest parts. On the coldest nights, the north shore usually experiences temperatures 5 to 10ºF lower than the south shore.

I have some palms in the ground, Carpentaria, Caryota, Acrocomia, Bismarckia, Dypsis lutescens, Ravenea, Syagrus sancona, Thrinax, Wodyetia, that have done well over the last few years, but I know they won’t last forever. I didn’t protect or move anything this winter. The only damage I had was a little frost damage on the foxtail and a potted Prichardia that lost all its fronds due to frost but has already put out a new one.

In New Orleans we don’t have dry and rainy seasons as in south Florida. We get about 65 inches (165 cm) spread evenly throughout the year. My climate is very similar to John and Faith’s in Myakka. I can still hear John saying “Kate, you got this palm at your place? It took 22°F here so you need to plant it”, as we walked around his place and then he loaded me up with many great palms to take home.

When referring to climates, I find it’s best to use actual data rather than the terms subtropical or USDA Zone 9. This information is included in my signature.

Kathryn

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amazondk

I posted this on a different thread, but it probably is more relevant here.  Brazil is more than 92 percent within the line of the tropics.  But, there are various climate zones within this area.   This map is from the Brazilian goverment and has a few erros in English, but makes sense.  The climate zones here a dvided between:

Equatorial

Tropical (equatorial zone)

Tropical (western, northeast)

Tropical (central Brazil)

Temperate

These areas are then sub divided by length of the dry season, if there is one.  For native vegetation this is a key factor in species composition.  My area is Equatorial superhumid - subdry.  I don't really mean know what they mean by subdry, but it must be some dry season, but not defined.  We nornally have from 1 to 3 months of dry season.  And, many years there is really not much of a marked dry season as it still rains fairly frequently, although in rapid downpours.

The area that is considered temperate in this map may be considered sub-tropical in other areas.

MAPA01.jpg

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Dave-Vero

Don, that looks like a great climate map for Brazil.  If only there were an equivalent for the US and Caribbean.

Here's the very useful http://www.klimadiagramme.de/ that uses (I think) the same climate classification system.  

And here's a site from Universidad Complutense in Madrid:  http://www.globalbioclimatics.org/

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SubTropicRay

I will refer to this often Kate.  Thanks for sharing.

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Neofolis

Despite global warming, I think they should move all of those zone boundaries nearer to the equator.  Particularly continental climates at some of the latitudes mentioned don't fit the climate descriptions as I would think of them.

Winnipeg is roughly the same latitude as here, but has an average January low of -23°C/-9°F and an average July high of 26°C/79°F.  Temperate? I wouldn't really describe that as a subtle change and whilst the summer high is not burning hot the winter low is definitely freezing cold in my opinion.  I suppose it's relative and compared with some regions of the antarctic it is quite mild, but then there are areas further north of Winnipeg that are much colder, before you reach the arctic circle.

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chris.oz

Kathryn,

Just to clarify some points:  dont forget  the equatorial zone.   Hot and humid all year round, no monsoon, no dry season, no cyclones.  This zone straddles the equator +-5 degrees of latitude.  Singapore, Rwanda, Java, Irian Jaya fall into this category.  This is the true home of  cyrtostchys renda.

Also remember that tropical includes dry [ desert] and seasonally dry areas.   The latter experience the monsoon and are hit by cyclonic storms and really never have frosts at sea level.

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amazondk

Chris,

Our climate is equatorial and we have a defined dry season.  This may only be 3 months but is very significant.  I have been driving north and south of the equator a lot lately where the seasons are reversed.  Even though this is only 800 kms from here to there the difference is marked.  As shown on the map I posted above very few areas in Brazil within the equatorial zone do not have marked dry seasons.

dk

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SubTropicRay

These classifications are broad descriptions.  They've lumped Mediterranean climates into the sub-tropics and equatorial into tropical.

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