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CLIMATOLOGY
Lebanon benefits from the mediterranean climate with its two distinct
seasons. It is subject to two opponent influences:
- To the west, the typical mediterranean climate characterized by a rainy
season in winter and a dry and hot season in summer; spring and autumn are
very short,
- To the east, the hot and dry climate of the arabic peninsula.
RAINFALL
Rainfall occurs mainly between october and april (70 % of the
total rain is recorded
between december and february); the dry season prevails between june and
october).
However, altitude and continentality bring important
differences to the rainy regime:
-the
western façade receives a good amount of rain because of the
presence of the "Mount
Lebanon" chain which stops the humid air masses coming from the west and
the south
west:,
so that rainfall on the Coast exceeds 700 mm; in altitude the
amount can even
reach
1500 mm and snowfall occurs starting from 1600 m, where it remains during
several
months.
Unfortunately, reliable data on the real amount of snowfall are not available;
however
the
CREEN (Centre Régional de l'Eau et de l'Environnement- Regional Center for
Water and
Environment) from the Saint-Joseph
University undertakes presently snow measurements
and samplings
for a better knowledge of snowfall in Lebanon,
-in the
Bekaa valley, rainfall decreases from the south to the north so that
climate turns nearly
dry in the
north of the Bekaa as the following data show:
- 800 mm at Karaoun- Central Bekaa,
- 600 mm at Rayak- Central Bekaa,
- 400 mm à Baalbeck,
- 250 mm au Hermel (extrem north of the Bekaa).
TEMPERATURES
The lowest monthly temperatures are recorded during the
months of december and january, and the highest take place in july and
august.
On the Coast, mean temperatures vary between 7o C in december-
january and 27o C in july-august. In the Central Bekaa, temperature
vary between 5,5o C and 24o C (Ksara Station);
whereas frost is unknown on the Coast, it is frequent in the Bekaa where annual
thermal amplitudes are high.
RELATIVE HUMIDITY
On the Coast, relative humidity is high (monthly mean
values vary
between 64% in november and 73% in august) because of the maritime influence,
but in the inland region the variations are more important (average values are
76 % in january and 44 % in august).
EVAPORATION
Field measurements of Potential Evaporation have been made by the Agricultural
Research Institute in different locations. Measured values
are the following:
|
Coast |
Bekaa |
| Annual values
Mean daily value |
1300 à 1350 mm
7 mm |
1330 to 1400 mm
11 mm |
|
