Climate
Due to the location
of Sri Lanka within the tropics between
50 550 to 90
510 north latitude and between 790 42’ to 810
53’ East longitude, the climate of the island could be defined as tropical.
Topography
The central part of
the southern half of the island is mountainous with height more then 2.5 km.
The core regions of the central highlands contain many complex topographical
features such as ridges, peaks, plateaus, basins, valleys and escarpments. The
remainder of the island is flat except for several small hills in the lowlands.
These topographical features strongly affect the spatial patterns of wind,
seasonal rainfall, temperature, relative humidity and other climatic elements,
particularly during the monsoon season.
Rainfall
Rainfall in Sri Lanka has multiple origins. Monsoonal, convectional and expression rains account for a major share of the annual rainfall. The mean
annual rainfall varies from under 900mm in the dries parts (southeastern and
northwestern) to over 5000mm in the wettest part (western slopes of the central
highlands). (Pica. 1)
Temperature
Sri Lanka’s position between 50
and 100 north latitude endows the country with a warm climate
including moderate ocean winds and considerable moisture. The mean temperature
ranges from as low as 15.80C in Nuwara Eliya in the Central Highlands
(where frost may occur for several days in the winter) to the hottest
temperature of 290C in Trincomalee on the northeast coast (where
temperature may reach 370C). The average yearly temperature for the
country on a whole ranges from 260C to 280C. Day and
night temperatures may vary from 4 to 7. January is the coolest month, causing
people, especially those in the highlands, to wear coast and sweaters. May, the
hottest period, precedes the summer monsoon rains.
Regional differences observed in air
temperature over Sri Lanka are mainly due to altitude, rather than to latitude.
The mean monthly temperature differ slightly depending on the seasonal movement
of the sun, with some modified influence caused by rainfall. The mean annual
temperature in Sri Lanka is manifested largely as standardized temperatures in the
lowlands and rapidly decreasing temperatures in the highlands. The mean annual
temperature varies between 26.50C to 28.50C in lowlands up to an altitude of
100m o 150m with an annual temperature of 27.50C. In the highlands, the
temperature falls quickly as the altitude increase. The mean annual temperature
of Nuwara Eliya, at 1800m above the sea level, is 15.90C. The
coldest month with respect to mean monthly temperature is generally January,
and the warmest months are April and August.
The mean annual temperature varies from 270C
in the coastal lowlands to 160C at Nuwara Eliya, in the central
highlands (1900m above sea level).
