FREQUENCY OF SIX-MONTH 
EXTREME DROUGHTS 
More than 14 occurrences 
Figure 1.7. Frequency of occurrence of six-month 
droughts in Texas, after Riggio and others, 
1987(9). 
OA 9689 
300 mi 
400 km 
E 
EXPLANATION 
Wind speed (knots) 
I- 3 
4-7 
8-10 
II- 13 
14-18 
QA 9690 
Figure 1.6. Wind rose for summer (upper diagram) and winter 
(lower diagram) winds at Houston Intercontin¬ 
ental Airport, 1971-1980. Summer is June-Aug¬ 
ust; winter is December-February, after Larkenand 
Bomar (1983). Length of the bar in a rose indicates 
the percent of days per three months the wind blows 
from a given azimuth. 
13 
