91. Winds . Since the wind speed and direction data for 1980 were ob- 

 tained every 6 hours (i.e., four times per day), the summaries are believed to 

 be far superior to those previously published, which were based on only one 

 daily value. No attempt will be made to compare the data summaries to prior 

 years except for a brief explanation of why the data are believed to be more 

 representative and less biased. 



92. Land-sea breeze, weather fronts, and cyclonic and anticyclonic 

 pressure systems all can cause rapid changes in both the wind speed and 

 direction. 



93. During March through September, the air temperatures were warmer 

 than the seawater; likewise, from January to February and October to December, 

 the air temperatures were colder. These temperature differences, along with 

 differences in land temperature, can create daily coastal breezes which vary 

 direction from morning to evening. Passage of weather systems can also cause 

 the wind direction to change. Figure 8 shows all occasions during 1980 when 

 the measured wind direction changed from offshore to onshore or vice-versa be- 

 tween 0700-1300, 1300-1900, and 1900-0100 hours. Onshore implies an easterly 

 component of direction, while offshore is westerly; half arrows indicate the 

 shift was either from or toward a direction without an easterly/westerly com- 

 ponent; i.e., north or south. 



94. Figure 8 shows the following tendencies in wind direction changes 

 for 1980: (a) during the morning hours 0700-1300, when, typically, heating 

 occurs after sunrise, the wind directions change from offshore/westerly to 

 onshore/easterly; (b) conversely, in the evening from 1900-0100, during cool- 

 ing times after sunset, wind directions shift from onshore to offshore; 



(c) wind direction changes during the afternoon hours from 1300 to 1900 appear 

 mixed but show some correlation with the temperature differences between the 

 ocean and the air/land (see Figure 24 and paragraph 124). 



95. Measurements made once a day would be incomplete and would produce 

 significantly biased information. As noted in the data analysis section, all 

 wind information summaries except for the meteorological tables in Appendix A 

 were created from observations made every 6 hours. 



96. Measurements made every 6 hours, however, have the following 

 shortcomings: peak conditions can be missed; precise times when fronts pass 

 can only be bracketed; correlation to other physical phenomena, such as the 

 rise and fall of the tides, can be difficult; etc. Hourly meteorological 



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