give an adequate depiction of diur- 

 nal shifts in wind direction and 

 speed resulting from the differen- 

 tial heating of air and water sur- 

 faces or the passage of individual 

 winter frontal systems. It does, 

 however, indicate the predominance 

 of different seasonal factors con- 

 trolling wind. On a seasonal basis, 

 highest average wind speeds tend to 

 occur in late winter and early 

 spring, and lowest speeds during the 

 summer. High localized winds of 

 short duration occur occasionally in 

 connection with summer thundershow- 

 ers and with cold fronts moving 

 across the state during other sea- 

 sons (Bradley 1972). Wind speeds 

 associated with convective systems 

 follow a diurnal pattern. On a 



typical day, wind speeds are lowest 

 in the nightime, increase during the 

 daylight hours to a peak in the af- 

 ternoon, and then decrease again in 

 the evening (Dames and Moore 1978). 



Synoptic scale influences are 

 associated with the passage of the 

 front, as previously described, 

 rather than with diurnal patterns 

 (Warzeski 1977). The influence of 

 synoptic scale systems on prevailing 

 wind direction is evidenced by the 

 northerly component of the prevail- 

 ing wind directions for the months 

 of October through January in 

 Table 5. 



Wind direction and speed tend 

 to vary with height above the 

 ground. The variation of wind di- 

 rection with height is not always 

 uniform, but wind speed generally 

 increases with height over the flat 

 terrain of the Everglades/Bay/Keys 

 basin (Dames and Moore 1978). Sea- 

 sonal variations of wind speed and 

 direction at the 950 mb level (0 to 

 610 m or to 2000 ft) are presented 

 in Figure 13. Dames and Moore 

 (1978) examined the low-level wind 

 patterns at 150m, 300m, and 500m 

 (492, 984, and 1640 ft) at Miami. 



They concluded that: 



"During both the morning and evening 

 at all three levels, winds are pre- 

 dominantly from the east and south- 

 east. Furthermore, the mean wind 

 speeds of the prevalent wind direc- 

 tions are greater than at Tampa and 

 Jacksonville. Certainly this is not 

 the case on each day of the year, 

 but it appears to be the most common 

 situation" . 



Table 5. Most common wind direction 

 and speed by month for 

 selected first order weather 

 stations [adapted from 

 USDC 1981a, 1981b, 1981c). 



3.4 TEMPERATURE 



The southern latitude and mari- 

 time influences are the primary con- 

 trols on the temperature regime in 

 the Everglades/Bay/Keys basin. The 

 climate is basically subtropical/ 

 marine characterized by a long, warm 

 summer followed by a mild, dry win- 

 ter (Bradley 1972). 



34 



