APPENDIX C 77 



180 150 120 90 60 30 



60 90 



150 ISO 



Figure C-27. Percent of time gradient < — 157 (N/ km): November. 



180 150 120 90 60 30 30 60 90 120 150 180 



60 



60 



70 



70 



180 150 120 90 60 30 



30 



60 90 120 150 



Figure C-28. Percent of ducting layers thicker than 100 m: November. 



