Diapositiva 1

Classificación climàtica Koppen-Geiger
Temperaturas, precipitaciones y reparto anual de éstas,
índice de aridez
Venezuela: Past weather and climate
Venezuela is the northernmost South American country with a long
Caribbean Sea coastline. The main chain of the Andes runs from west to
east, leaving a narrow coastal plain. To the west there is an extensive
marshy plain around Lake Maracaibo whilst to the south lies the large
lowland area around the Orinoco valley (the Llanos). This latter area has a
typical tropical climate with a single rainy season. Venezuela is unusual
among South American countries in that almost everywhere the main rainy
season is from April to October at the time of high sun. Towards the west of
the country there is a tendency for a double rainy season whilst the northern
lowland - particularly in the west - has a surprisingly dry climate for a
tropical coast.
The Venezuelan Andes are lower and narrower than those in other
countries, but there are some peaks up to 15,000 feet which carry snow all
year. There are many local variations of weather and climate as a result of
altitude. The northern slopes of the Andes tend to have less rainfall than the
southern side. Caracas shows signs of the relative dryness which affects
the northern coasts, having an annual average rainfall of about 840 mm
(33"). Daily average maximum temperatures have a very small variation
from 24 °C (75 °F) in January to 27 °C (80 °F) in April and May. Sunshine
amounts are moderately high varying from 6 to 8 hours per day. Annual
rainfall in the mountains is generally around the 1,000 mm (40") level, whilst
the plains around Lake Maracaibo has an annual rainfall figure of 580 mm
(23"). This latter area is hot all year, with typical daily average maximum
temperatures in the mid-30s °C region. In the Llanos region of the Orinoco
valley there is an annual average rainfall of about 1,500 mm (60"),
temperatures stay in the mid-30s °C range with very little variation, and high
humidities make this to be an uncomfortable region.
Peru: Past weather and climate
• Peru is a large country with a long Pacific coastline. The central
portion includes the great mountain and plateau region of the Andes
with many peaks over 20,000 feet together with extensive plateau
areas between 10,000 and 14,000 feet.
• The coastal district has an unusual type of dry desert climate,
caused by the northward-flowing cold waters of the Humboldt
current. These cold waters maintain low temperatures for a tropical
latitude right up to the equator and there are very small differences
from month to month. The dryness is so marked that in some places
several years have passed without appreciable rain.
• However, in some northern coastal districts, there is a remarkable
change of weather for a few weeks every few years. The
temperature rises and torrential rain may fall for those weeks
causing widespread damage. This is the well-known El Nino effect
and is most likely to occur in December and January. This coastal
strip is prone to extensive low cloud, fog and drizzle (called garua).
At Lima, which is largely representative of the coastal strip, daily
average maximum temperatures range from 19 °C (66 °F) in July
and August, to 28 °C (82 °F) in summer. The city has just 1-2 hours
of sunshine each day on average in winter rising to 6-7 hours in
summer. The climate of the central portion is very similar in many
ways to that described for the equivalent area of Brazil.
Chile: Past weather and climate
Chile is a remarkably-shaped country, extending 2,600 miles between 22
and 55 degrees South, but having an average breadth of between 100 and
200 miles.The east of the country is very mountainous, with peaks up to
16,000 feet. South of Santiago the mountains are lower and more broken,
but the whole country is rugged with hundreds of small offshore islands.
Much of Chile therefore has a mountain climate with perpetual snow and
glaciers. Precipitation is light in the northern mountains, and so the snowline
is high. Away from the mountains, the north is a desert. Most of the
population lives in the lowlands of central Chile, whilst the southern part of
the country is rugged and densely forested with a cool wet changeable
Northern Chile is one of the world's driest regions. Here, despite being
almost rainless, the weather is often cloudy and cool. Annual average
rainfall totals can be as low as 14 mm. Average daily maximum
temperatures range from 17 °C (63 °F) in July to 28 °C (82 °F) in March.
Central Chile has a Mediterranean climate with warm and virtually rainless
summers, whilst the winters are mild and moderately wet. Frost and snow
occasionally occur inland, but are rare on the coast.
At Santiago, daily average sunshine hours range from 3 in June and July to
11 in January and the daily average maximum temperatures range from 14
°C (58 °F) in June to 29 °C (85 °F) in January.
Southern Chile tends to be wet all year round, featuring frequent disturbed,
changeable weather. Annual precipitation can be as high as 5,000 mm
(200") much of which falls as snow farther south and on the higher
mountains. On the coast, winters are rarely very cold, but summers are cool
and cloudy.
Argentina: Past weather and climate I MET
The Argentine Republic is a large country about one-third of the size of the
United States. The centre and east are mostly low and flat, but the west is
very mountainous rising to the Andes peaks, some of which reach over
22,000 feet. The northern Andes have surprisingly low precipitation so that
the snowline may be as high as 20,000 feet. The southern Andes have
much more precipitation, and there are many glaciers and permanent
Because of these great altitude and latitude differences, there are many
weather and climate differences. The country can be split into four broad
climatic regions: the east central region (Pampas); the north-eastern
interior; western Argentina and southern Argentina (Patagonia). The
distinctive mountain climate of the High Andes should also be added.
East central Argentina (including Buenos Aires) also known as the Pampas,
has an adequate rainfall of between 500 mm (20") to 1,000 mm (40") per
year. The area has mild winters and warm summers within more rainfall
during the summer months. Most of the rain falls on just a few days, so that
wet changeable weather is not frequent, but the rain is often heavy. Average
daily maximum temperature at Buenos Aires range from 14 °C (57 °F) in
June and July to 29 °C (85 °F) in January. Average sunshine hours per day
range from four in June to nine in the summer months. The region does not
often experience heat or cold extremes, but frost may occur in most winter
months but is not prolonged or severe. This is the most important
agricultural region of the country and occasional drought is the main
economic hazard.
Argentina: Past weather and climate II MET
The north-eastern interior has a warmer climate than the Pampas and, towards the
north it is tropical or near-tropical. Temperatures remain quite high throughout the
year, average daily maxima at Santiago varying from 21 °C (70 °F) in winter to 36 °C
(97 °F) in January. An extreme temperature of 46 °C (115 °F) has been recorded in
one January. The combination of heat and humidity may be uncomfortable in
summer, as this is the cloudier wetter season. Occasional cold spells in winter may
bring temperatures near or below freezing for a few hours, but generally the winters
are mild or even warm. Average sunshine hours per day are similar to the Pampas
Western Argentina is a dry region. Even on the highest peaks snowfall is light. The
eastern slopes and foothills of the Andes form a semi-arid region and the lowlands
are virtually deserts. Annual rainfall of less than 250 mm (10") is not uncommon.
Droughts are frequent here and often prolonged. Rainfall is more frequent in summer
months which are often hot and sunny. Sunshine hours range from 10 hours per day
in summer to about 7 in winter. At Mendoza daily average maximum temperatures
range from 15 °C (59 °F) in winter to 32 °C (90 °F) in summer.
Southern Argentina is a dry region with (in terms of temperature and changeable
weather) a cool temperate climate not unlike that of the British Isles. The dryness,
however, is unusual for such a high latitude. Towards the west of the region, rainfall is
greater as cloud spills over the western side of the Andes. In the extreme south of the
region, the summers are distinctly cool. The winters are long with frequent frost and
snow, but the ocean's influence ensures that the cold is never prolonged or severe.
The summers are generally cool and cloudy with brief spells of fine pleasant weather.
Brazil: Past weather and climate I MET
• Brazil is slightly smaller than the United States. As it is one of the
few South American countries not to include the Andes mountains,
there are no permanent snowfields in Brazil. The country is split into
four distinct climatic regions: the Amazon Basin, the Brazilian
plateau, the coastlands within the tropics and the southern states.
• The Amazon Basin is the largest area in the world with a typical
equatorial climate. Rainfall in some places can exceed 2,000 mm
(80") and there is no real dry season. Tropical temperatures (27-32
°C/81-90 °F) are typical. Frost is unknown, but in the south of the
region, occasional cold spells (friagem) cause night temperatures to
fall below 10 °C (50 °F) making it most uncomfortable for the people.
Daytime temperatures of 38 °C (100 °F) are rare, but the high
humidity and monotony of the temperatures can make conditions
very unpleasant.
• The Brazilian Plateau is another very large region, but being south
of the Amazon Basin and at a moderate altitude, it has a very
different climate. There is a very distinct wet season at the time of
high sun, with almost all the rainfall (about 1,500 mm/60") falling
between October and April. The dry northeast of the region has a
much lower average rainfall (in some places less than 750 mm/30"),
but it is also very irregular from year to year, causing prolonged
droughts. The tropical east coast (including Rio de Janeiro) has a
typically hot tropical climate, although there are significant
differences in the season of greatest rainfall from north to south.
Brazil: Past weather and climate II MET
• Near the Amazon mouth all months are wet, but the greatest
rainfalls occur from December to May (in excess of 300 mm/12" per
month). Further south (e.g. Recife) the wettest months are May to
August, although amounts tend to be lower. Further south still (at
Rio) the wettest period is November to April. Nowhere on this coast
do maximum temperatures rise so high as to be uncomfortable, but
the combination of warmth and high humidity can be unpleasant at
night. Daytime heat is often tempered by sea breezes, but
temperatures never drop very low. Frost is unknown on the coast,
but in the hills occasional frosts may damage the coffee crop.
• The southern states have a warm temperate climate, although on
the coast a distinct cooler season can produce frosts. Winter has a
real significance in this region, and the difference between the
seasons is determined by temperature rather than rainfall. The area
is often affected by invasions of cold air from the Antarctic, but
during summer, temperatures can rise to levels similar to the tropical
regions. The region has a healthy and pleasant climate with an
average of 8-9 hours of sunshine a day in summer. On the higher
land, frosts are common, but snow is very rare. Inland the wettest
months are during the summer in contrast to the coast.

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