low altitude northern winds in the rear of the cyclone result blocked upstream of the
Alboran coastal mountain ranges, strong pressure gradients develop across the
ranges and the air flows southward through the gaps in the ranges producing
northwesterly high winds over the Alboran Sea, locally called terral winds. As the
elevation of the land surface is higher on the windward side than on the leeward side,
terral winds will be warm because of adiabatic warming, and their relative humidity
when it completes its descent may be very low. The airflow off the north coast of
Alboran tends to be complex with gusty winds inside and downstream from the
canyons and lighter winds elsewhere, but the extreme warmth and dryness of the
downstream air masses are pervasive.
Easterly high winds, denominated levanter winds, occur very frequently in the
Strait of Gibraltar. Levanters can be synoptic or mesoscale events. Synoptic
levanters are regional winds that extend far beyond the Strait, from the Mediterranean into the Atlantic covering the Alboran Sea and part of Iberia and reaching
upward into the upper troposphere. Isobars present east–west orientation. The
interaction of the easterly flow with the mountains that close the Alboran Sea to
the west, and even the flow interaction with the further south Atlas Mountains, make
that wind in the Strait and over the Gulf of Cadiz acquire characteristics of regional
downslope windstorm. A low-pressure center locates offshore the Atlantic coasts of
Morocco, which sometimes is observed as a low cloud vortex in satellite images
(Fig. 3.12).
Mesoscale levanters occur only over immediate Strait and usually below 1000 m
(Dorman et al. 1995). Winds increase to the west, so that highest velocities take place
near Tangier, and isobars are aligned at right angles to the Strait. A mesoscale
surface low appears centered west of the narrowest part of the Strait near Tangier,
so that winds are ageostrophic. Mesoscale levanters are a consequence of the cold air
1400
1200
1000
800
600
400
200
0
1942
1944
1946
1948
1950
1952
1954
1956
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
Fig. 3.11 Annual precipitation (mm) recorded at AEMET Malaga station (blue line) and 9-years
running precipitation mean (red line). Source: AEMET
3 Alboran Sea Area Climate and Weather
41
Alboran coastal mountain ranges, strong pressure gradients develop across the
ranges and the air flows southward through the gaps in the ranges producing
northwesterly high winds over the Alboran Sea, locally called terral winds. As the
elevation of the land surface is higher on the windward side than on the leeward side,
terral winds will be warm because of adiabatic warming, and their relative humidity
when it completes its descent may be very low. The airflow off the north coast of
Alboran tends to be complex with gusty winds inside and downstream from the
canyons and lighter winds elsewhere, but the extreme warmth and dryness of the
downstream air masses are pervasive.
Easterly high winds, denominated levanter winds, occur very frequently in the
Strait of Gibraltar. Levanters can be synoptic or mesoscale events. Synoptic
levanters are regional winds that extend far beyond the Strait, from the Mediterranean into the Atlantic covering the Alboran Sea and part of Iberia and reaching
upward into the upper troposphere. Isobars present east–west orientation. The
interaction of the easterly flow with the mountains that close the Alboran Sea to
the west, and even the flow interaction with the further south Atlas Mountains, make
that wind in the Strait and over the Gulf of Cadiz acquire characteristics of regional
downslope windstorm. A low-pressure center locates offshore the Atlantic coasts of
Morocco, which sometimes is observed as a low cloud vortex in satellite images
(Fig. 3.12).
Mesoscale levanters occur only over immediate Strait and usually below 1000 m
(Dorman et al. 1995). Winds increase to the west, so that highest velocities take place
near Tangier, and isobars are aligned at right angles to the Strait. A mesoscale
surface low appears centered west of the narrowest part of the Strait near Tangier,
so that winds are ageostrophic. Mesoscale levanters are a consequence of the cold air
1400
1200
1000
800
600
400
200
0
1942
1944
1946
1948
1950
1952
1954
1956
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
Fig. 3.11 Annual precipitation (mm) recorded at AEMET Malaga station (blue line) and 9-years
running precipitation mean (red line). Source: AEMET
3 Alboran Sea Area Climate and Weather
41