As I said several days ago, there are many diferent elements that can be taken into account in order to feature a place’s climate. As climatologic parameters are way too diverse, we are forced to choice the ones we consider they show best the whole picture. We usually stick to temperature and precipitation, and from them we may infer what the others work like. I think the main elements are the following:
- Average temperature
- Average precipitation
- Precipitation seasonality (expressed as the % of precipitation fallen during the high-sun semester
- Temperature range (difference between the average temperature of the hottest month and the average temperature of the coldest month)
For instance, if a place is cool/cold with narrow annual thermal range and little precipitation, most of it concentrated during summer, we can infer it’s a tropical/subtropical highland site where relative humidity is very low, daily ranges of temperature are very high, there are lots of sunshine hours and most rain falls during brief afternoon thunderstorms. Not always is it predictable, but we can get some clues. So, different climate classifications were elaborated in order to group different places with allegedly similar features, but they often ended up backfiring throughout the emergence of very unalike sites within the same group, places that doesn’t fit in the general idea of its climate type, etc.
This time I will get by without
lockers and embrace a more gradualistic approach, as well as a more experimental one. This XY graph correlates Average precipitation and Precipitation seasonality for more than 250 stations of Argentina, and provides further information via coloring to show ranges of average temperature. As we have come short of dimensions, annual temperature range is missing, which is ultimately the weakest link when portraying the climate diversity of Argentina, as everywhere in the country is encompassed between amplitudes of 6ºC and 20ºC, courtesy of the never-ending oceans of the Southern Hemisphere. So, annual range is not that important in this characterization.
X-axis = Average precipitation
Y-axis = % of precipitation fallen during the high-sun semester
Color series = Average temperature
About the colors and ranges used, it is necessary to remark that in Argentina there are not places whose average temperature is over 25ºC, but there are tons of high altitude sites where it is below 0ºC (average temps in Argentina go from -19.5ºC to 23.5ºC approximately). Unfortunately these areas are mostly lacking of reliable precipitation records. To clarify, such areas as a whole show exactly the same precipitation patterns (and hence, distribution in the chart) as the stations from the 0-5ºC range.
Virtually every corner of the graph is taken up by a station, which shows the impressive climate diversity when combining both amount of precipitation and yearly distribution. In terms of average temperature, the upper half is completely covered by the whole range of average temperatures that occur in the country. The places with dry summers are less diverse in this apartment, being restricted to below 15ºC sites, with the wetter areas being the most homogeneous.
The various country’s regions can be roughly captured on to the graph, each one having their own features so that they occupy specific parts of the Cartesian Plane. There are three main peak precipitation areas, all of them with markedly different seasonal patterns:
- The first one occurs in Northwestern Argentina (“Noroeste”) and is caused by summer orographic rain in the eastern slopes of the Andes.
- The second peak precipitation area is the main of the country, covering the lowlands of the Río de la Plata basin (“llanura platense”) and having its core in the extreme Northeast, which is perpetually affected by the Atlantic high that provides humidity and precipitation throughout the year.
- The third one has an orographic component too, occurs in the Patagonian Andes (“Patagonia Andina”), especially between 40 and 45ºS. The seasonal shift of the Pacific high causes the typical dry-summer Mediterranean/Oceanic climates from the western sides of the landmasses. Overall altitude makes them colder than the usual Mediterranean climates.
- There is a (smaller) fourth area with maximums occurring in Tierra del Fuego. It’s rather a split up of the Patagonian maximum, but it’s different in which at those latitudes precipitation seasonality is lost.
The wet branches converge in the arid west of Argentina, constituted by the cooler and winter rain oriented Patagonian steppe (“
Patagonia”) and the warmer and summer rain oriented Central Western Argentina (“
Cuyo”). The Andean Plateau is the other component of the dry stripe of the country, shown in the upper left section of the graph, and included as part of the Northwestern. Due to the altitude, it’s as cool as Patagonia, but its extreme rainfall seasonality makes it quite different.
Finally, the Central Andes (“
Andes Centrales”), despite the geographic proximity with the Andean Plateau, have a very different climate, with extremely dry summers, and -often- extremely snowy winters.
The following map shows the aforementioned precipitation peak areas and the location of the boundary between the Pacific high influenced areas and the Atlantic high influenced areas, that cause the opposite rainfall patterns. It also explains why the dry-winter and non-dry season areas cover a larger range of temperature whereas the dry-summer areas are just on the cooler side. The first ones span from lowlands of lower latitudes up to mountain peaks. The dry summer areas only appear in middle latitudes for lowlands.
Any questions and comments are welcome!
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