Two maps have been prepared (see Appendix C) that show the mean 

 and maximum annual number of thunderstorms in the region. Generally the mean 

 number of thunderstorms increases from east to west and inland from the shore, 

 with the smallest number occurring in eastern Connecticut and eastern Long 

 I sland. 



3.7 Tornadoes 



Tornadoes occasionally develop in air mass or pre-frontal thunder- 

 storm areas during the afternoon or evening. Most tornadoes in the region have 

 occurred in southwestern Connecticut and the risk of their occurrence decreases 

 eastward because of the stabilizing effect of the Sound. A table is furnished 

 (see Appendix C) that chronologically lists all known tornadoes in the region 

 since 1682. 



3.8 Cloudiness 



Cloud cover averages computed over the full day for the period 

 1951-70 are available from LaGuardia Field, New York and for the pet iod 1951- 

 69 from Westhampton Beach, New York. The annual march of mean cloudiness in 

 tenths for these two stations is shown on a graph prepared for this study (see 

 Appendix C) . Mean monthly cloudiness for the sunrise to sunset period for 

 Bridgeport, Connecticut and for k stations near the study area--Block Island 

 and Providence, Rhode Island; LaGuardia Field, New York and Hartford, Con- 

 necticut are shown on a separate graph. 



Annual mean sky cover averages about 60 percent over the study 

 region, but there is considerable variation both in time and space. Cloud 

 amounts over mainland interior areas are generally greater than over coastal 

 sections except from June through September. Western mainland interior areas 

 have greater cloud amounts than eastern areas whereas along the coasts cloudi- 

 ness is generally greater in the east than in the west. The greatest number 

 of clear days throughout the region occur in September and October. 



Comparisons among stations point out the influence of season and 

 the proximity to the Sound and Ocean on sky cover. Graphs have been pre- 

 pared for four stations to illustrate the controls operating on sky cover. 

 The graphs show the annual march of mean cloudiness and the percentage fre- 

 quencies for two classes of sky cover for the hours from 6 a.m. to 8 p.m. 

 (See Appendix C.) 



3.9 Wind 



The frequency distribution of the occurrence of wind direction 

 and speed reflects the passage of weather systems, the distribution of land 

 and water and the local exposure. Wind data in the Long Island Sound Region 

 are available for LaGuardia Field, New York and Bridgeport and New Haven, Con- 

 necticut. Data for Newburgh and Westhampton Beach, New York have also been 

 used for this study. All weather wind-rose diagrams for each of the four 

 seasons at these five stations are listed in Appendix C. 



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