Regional Contrail Number.
In order to make the analysis of the graphs, showing the number of contrails on a particular day at each station, easier they were grouped into regions; North (N), North West (NW), North East (NE) and South (S). Obviously the regions NW and NE are more obviously 'regions' that those stations grouped together into the N and the S categories, these N and S categories however do still make the analysis simpler as they reduce the number of graphs necessary.
Lancaster has not been included in any of the regions (although it is really part of the northwest) as it is the standard station that all others are compared to.
To see the results for a particular region click on a region on the figure below.
The National Contrail Network. Discussion and Conclusions.