Travel Guide:
Timor - Leste
The climate
Situated in the equatorial
regions, Timor presents two annual seasons
determined by the monsoon regime. The
accidented of the relief, direction of
the mountains and proximity to Australia
produces different meteorological features
among the distinct regions of the small
island. Classical climatic classifications,
because less apropriate to study the isothermal
climates of Indonesia, have been substituted
by others soly based on the rainfall records,
of which we have adopted Schmidt and Ferguson's.
Three climatic zones.
In the tropic regions,
where lies Timor, differences of temperature
are relatively small, so it's the pluviometric
regime that determines the vegetation,
the kind of meteorization of the soil
and consequently the possibilities of
culture and the proper extension of human
settlements.
Timor, due to it's
accidented relief, direction of the mountains
and proximity to the Australian continent,
the meteorological circumstances of the
island's distinct regions are variegated.
F. A. Soares attended
to annual precipitation, average temperature
and specially altitude and pluviometrical
quotients to climatically divide East
Timor into three zones. In the north,
the area from the coast to the 600 m bench
mark, very accidented, featuring an annual
average of temperature over 24 deg., weak
precipitation (below 1500 mm annually),
and with a very pronounced dry period
lasting five months. The mountainous zone
is comprised between the northern and
southern, above the 600 m level, with
temperatures under 24 deg., high precipitation,
superior to 1500 mm and a dry period of
four months. Finally, the southern zone,
which stretches from the coast to the
600 m mark, the relief less accidented,
having plains with great extension, exposed
to the winds of Australia, much more rainy
than the northern zone, with average temperatures
generally higher than 24 deg. and a dry
period of three months.
The
monsoons.
Situated in the equatorial
region, Timor presents two annual seasons
determined by the monsoon regime, which
are more defined than those of the large
islands of the Indian archipelago because
of it's proximity to Australia.
The winds that blow
from northeast (northwest or wet monsoon),
from November to May, carry thunderstorms
and great rainfalls whilst the moderate
winds of Australia, fresh and almost dry,
bring little rain and lower the temperature
mainly during the night. It's the southeast
or dry monsoon.
Nevertheless, between
one and the other differences in temperature
are almost insensible.
Altitude influences
precipitation since its higher as we move
to the inland. Distribution of rainfall
is conditioned by orographic causes --
such as nature and disposition of the
relief -- and distance of the sea.
The southern zone
adds much higher precipitation in comparison
with the northern what seems strange at
first, not only because of the monsoon
mechanism but also because of her higher
latitude and lower temperature. In fact
the north is more exposed to the NW (wet)
monsoon and the southern to the SE (dry)
monsoon. What happens is that Timor is
only 500 km far from the Australian continent
and as it's longitudinal axis is practically
perpendicular to the SW monsoon, the dry
winds coming from Australia attain humidity
while crossing the Timor sea, that is
lost through strong precipitation when
touching land and increasingly as leaping
the central chain, to arrive at the northern
side almost dry. Besides, the southern
zone has more extent plains, covered with
abundant vegetation, where therefore the
absolute humidity is higher.
During the NW monsoon,
the masses of moistured air brought by
the maritime winds, after a great passage
above the islands of the Indonesian archipelago
-- very accidented and with great altitudes
-- will loose humidity and be forced to
rise. As a result, precipitation over
Timor shall only happen where these masses
of air are subject to higher altitudes:
the north receives minor rainfall which
increases as reaching the central crest
and comes upon the southern zone.
In the northern zone,
the humid period, of five months lasts
from December to April and the dry period,
also during five months, goes form June
to October. Transition occurs in April.
In the mountainous zone, the humid period
(five months) begins in December and ends
in April, while the dry period (four months)
is comprised between July and October.
May and June is the period of transition.
The southern zone has a humid period of
seven months, from December to June alternated
with a dry period of three months: August,
September and October. July is the transition
month. In all three zones, November marks
the transition between the humid and dry
periods.
Pluvial
regime.
The
annual quantity of precipitation is exceptionally
high in the humid period and opposite
in the dry period. Amongst the three zones,
the northern lands are responsible for
the highest variations in the values of
the pluviometric quotient (quota with
which every month contributes for the
total precipitation of a year) whilst
the southern zone is the most homogenous.
Annual frequency rates
are low in general terms, the lowest in
the northern zone and less lower in the
mountainous zone. During the humid period
rates are relatively low considering that
80% of annual precipitation falls during
that time. There can be found a maximum
of 61 days in a hundred at Maubisse and
Atsabe (mountainous zone) and a minim
of 23 in Manatuto (northern zone). In
the dry period, decrease is parallel.
While in Central Europe and cereal regions
of North America there's to be expected
forty days with rain, in East Timor not
more than eleven in a hundred are rainy.
As usual in the tropical
regions, values of the pluviometric quotient
(between the precipitation of a period
and the days with rainfall) in Timor are
high. More intense raining is to found
in the southern zone, and less in the
North. The consequences of this are also
predictable: heavy showers bring little
benefit to the plants as the majority
of the water is lost by superficial draining,
which on the other hand, will carry out
an important role in the process of erosion,
depending on the nature of the terrain
and topographical conditions. On the contrary,
when rainfall intensity is weak, most
of the water infiltrates and is retained
in the soil, becoming part of it's economy.
The
temperature.
In
Timor, the annual average, diversely to
the precipitation, stands very regular.
During the NW monsoon, we can better sense
the heat, as there's no wind blown from
the land which in the SE monsoon refreshes
the constancy of temperature, mainly during
the night.
In the torrid zone,
duration of days and nights and meridian
heights of the sun suffer small variations,
and this way, differences between monthly
temperature averages are low. This isothermal
feature perfectly embodies Timor in the
Indonesian archipelago, where the most
notable factor and with increased influence
in the types of climates is precipitation.
Naturally the northern
and southern regions are hotter than the
mountainous, as temperature falls with
altitude. Absolute differences leap up
to less than 10 deg. in the most. In view
of the very accidented relief of the territory,
one often comes across rapid changes just
a few minutes drive if ascending some
hundred meters, like between Díli and
Dare (with a 4 or 5 deg. difference).
If we are to calculate
the deviations on the average temperatures
of the months in relation with the annual
references of the many regions, it's liable
to distinguish a hot and a cold period.
The first lasts between November and April
inclusive (at the time of the NW monsoon)
with the deviations being always positive
except in Liquiçá, Aileu, Fatu-Bessi and
Alas. The cold period (SE monsoon) goes
from May to October, generally presenting
negative deviations. The coldest month
is July and the hottest is November.
Humidity
and evaporation.
Humidity of the air
is normally higher between December--May,
obviously during the NW monsoon. Evaporation
is higher in the period of June--November,
variating inversely to precipitation,
temperature and humidity of the air which
are lower. This happens because in the
December--April period, (during the NW
monsoon), occurs an excess of precipitation
over evaporation while a deficit takes
place along May--November (SE monsoon).
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