Zone 6: A New Designation For Cooler Weather?

The designation of “zone” was first used in the United States in 1934 to designate a climate region (see map). Since then it has been widely applied throughout the world. However, there are some areas where its use is less common than others. One such area is the tropics and subtropical regions of North America, Europe, Africa and South America. These zones have not been well studied because they tend to experience extreme weather conditions during the year.

In recent years, scientists have begun studying these areas more closely. They’ve found that many of them do indeed experience cooler temperatures during the summer months than other parts of their respective countries or continents.

So why don’t tropical and subtropical areas get designated as “cooler” climates?

One reason could be due to the fact that most of these areas are still relatively warm year round. Another reason might be that many of them are mountainous, which means they receive little rainfall and thus coolness doesn’t occur as much. Still another factor may be the fact that many of these areas are very dry during the winter months. Thus, even though they experience cooler temperatures during the summer months, they aren’t necessarily experiencing cold winters either.

Even the designation of “subtropical” doesn’t quite cover the temperature variations that occur in these regions. For example, areas located along the southern Atlantic coast of the United States (from North Carolina to Texas), even though they have subtropical climate characteristics, experience greater temperature variation than their counterparts in California and Florida. These southern states also experience a greater degree of rainfall during the winter months, although it is not enough to really affect their drought conditions.

The following is a list of some of the areas that are experiencing cooler weather conditions:

Northwestern Andean Mountain Chain (Parts of Colombia, Ecuador and Venezuela)

The mountain chains located in the Andes region of South America experience a wide range of weather conditions. Some areas experience colder weather than parts of New Zealand and some at the highest elevations experience frost during the winter. These regions also experience a great deal of wind and fog.

Why?

Because they are at a higher elevation and the wind blows downward off the mountains creating cold air currents.

This area could be classified as a “zone” in that it experiences cool weather conditions (even though it’s located in a tropical region). The mountain range is broken up into several sections:

The Eastern Andean Zone

This zone consists of a long mountain range, which runs east to west along the length of Venezuela and parts of Colombia. Its elevation varies from 1,000 to 5,000 feet. The Eastern Andean zone experiences a great deal of rainfall during the rainy season (June to December).

The area also receives plenty of fog from the sea. It’s here where Venezuela’s famous Angel Falls (the highest waterfall in the world) is located.

The area just north of the Eastern zone consists of a drier area known as the llanos or “tropical plains.”

The Western Andean Zone

This area consists of a series of mountain ranges that run west to east along the length of Colombia and Ecuador. The elevations in this area range from 5,000 to almost 15,000 feet and experiences colder weather than the Eastern zone. The topography here is also more rugged than its eastern counterpart.

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The town of Pasto (located in the southwestern part of Colombia) is considered to be the “equatorial” city of the Western zone. This is due to the fact that it’s located right on the 5,000 foot line of the mountain range.

The Andes Mountain Range

In general, the Andes Mountain range extends more than 3,000 miles along the entire western portion of South America and is the longest mountain range in the world. The highest peak in this chain (Aconcagua) reaches almost 23,000 feet. The weather in the Andes Mountain range is very unpredictable.

Most of the area experiences a rather dry climate, yet some locations receive a great deal of rainfall during the winter months.

The area also experiences a phenomenon known as El Nino, which is a period of warmer sea surface temperatures that causes the upwelling of warmer water from beneath the ocean depths. This action disrupts the normal weather patterns and causes floods along certain coastal areas and droughts in others.

The Eastern Andean Zone

This area consists of another drier, mountain range that runs north to south along the eastern coastline. These mountain ranges are not as high or rugged as the other Andes Mountain Ranges (both eastern and western). The elevations in this area rarely exceed 4,000 feet.

Most of the Eastern Andes experience a very arid climate with little rainfall during the year. The temperatures in this area are also much hotter than other parts of the Andes zone.

A warming trend known as El Nino affects this area in a different way than the western Andean zone. The eastern mountain range tends to experience an increase in rainfall during the winter months, which causes flooding in some locations.

The Deserts

There are three major deserts in Venezuela (and one that is disputed by geographers).

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The first desert is known as the llanos or “tropical plains.” This desert consists of a vast, very dry grassland with scattered pools of water. Most of the llanos are located in Venezuela and Colombia.

In fact, the name “Venezuela” is derived from the phrase “vacía de las llanuras” which means “empty of the plains.”

The second desert is known as the “Northern Andes.” This desert consists of a series of mountain ranges and flat lands located north of the Andes Mountains. This area is considered to be the most arid in all of the Andes region.

The Atacama Desert in Chile is similar to this region.

The third desert is known as the “Southern Andes.” This desert is located immediately south of the Southern Andes Mountain Ranges. This desert experiences a scant amount of rainfall.

The region is also characterized by several salt basins.

The Coastal Zone

The coastal zone consists of several landforms and climate types. In general, there are two major types of coasts in Venezuela. The first coastal area consists of low, flat, marshy plains that are adjacent to the Caribbean Sea.

These coastal plains are inundated by seawater during high tide and are transformed into salt marshes during low tide.

The second coastal area consists of low hills or cliffs that drop straight into the ocean. The steep cliffs have eroded over time forming large caverns and tunnels that are inhabited by wildlife. Some of the caverns extend far into the heart of the cliffs.

The Venezuelan Coastal Mountains extend along the entire coast line of Venezuela. The mountains are not very high (only reaching a few thousand feet), but they are steep and rugged enough to prevent easy access to the Caribbean Sea.

Sources & references used in this article:

Management of flowering in three tropical and subtropical fruit tree species by TL Davenport – HortScience, 2003 – journals.ashs.org

Winter chill models in a mild subtropical area and effects of constant 6 C chilling on peach budbreak by P Allan, G Rufus, GW Matthee… – … Symposium on Growing …, 1993 – actahort.org

Quantifying bee assemblages and attractiveness of flowering woody landscape plants for urban pollinator conservation by BM Mach, DA Potter – PLoS One, 2018 – journals.plos.org

The effect of the density of flowering individuals on the mating systems of nine tropical tree species by DA Murawski, JL Hamrick – Heredity, 1991 – nature.com

Sixty trees from foreign lands by EL Little – 1961 – books.google.com

Effect of repeated sprays of 6-benzyladenine on the formation of sylleptic shoots in apple in the fruit-tree nursery by SJ Wertheim, EN Estabrooks – Scientia Horticulturae, 1994 – Elsevier

… -zone temperatures affect phenology of bud break, flower cluster development, shoot extension growth and gas exchange of ‘Braeburn’ (Malus domestica) apple trees by DH Greer, JN Wünsche, CL Norling… – Tree …, 2006 – academic.oup.com

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