Geoscience Reference
In-Depth Information
30°W
20°
10°
0°
10°
20°
30°
40°
50°
60°E
cA
mP
mA
cA
50°N
50°N
cP
cP
mT
40°
3
40°
4½
mP
60
mT
1
4
cT
51
28
30°
7½
30°
14
1½
4½
1
0
1000
km
cT
10°
0°
10°
20°
30°
40°
Figure 10.27
Tracks of Mediterranean depressions, showing average annual frequencies, together with air-mass
sources.
Source: After Weather in the Mediterranean(HMSO, 1962) (Crown Copyright Reserved).
Table 10.3
Number of days with a strong mistral in the South of France
Speed
J
F
M
A
M
J
J
A
S
O
N
D
Year
11m s
-1
(21 kt)
10
9
13
11
8
9
9
7
5
5
7
10
103
17m s
-1
(33 kt)
4
4
6
5
3
2
0.6
1
0.6
0
0
4
30
Source: After Weather in the Mediterranean(HMSO, 1962).
Perpignan to the Rhône in 1924-1927). Similar
winds may occur along the Catalan coast of Spain
(the
tramontana
, see
Figure 10.30
) and also in the
northern Adriatic (the
bora
) and northern Aegean
Seas when polar air flows southward in the rear of
an eastward-moving depression and is forced over
the mountains (cf. Chapter 5C.2). In Spain, cold,
dry, northerly winds occur in several different
regions.
Figure 10.28
shows the
galerna
of the
north coast and the
cierzo
of the Ebro valley.
The generally wet, windy and mild winter
season in the Mediterranean is succeeded by a
long, indecisive spring lasting from March to
May, with many false starts of summer weather.
The spring period, like that of early autumn, is
especially unpredictable. In March 1966, a trough
