Night Light of Castro-Urdiales (Cantabria) from space (Spain) Src. Average luminocity for 10x10km area is 26.4825% and for 50x50km: 13.8629%.
Square area 10x10 km:
 2.38%
 2.86%
 6.98%
 4.29%
 2.7%
 1.9%
 3.33%
 3.02%
 3.02%
 28.41%
 41.11%Square area 50x50 km:
 2.43%
 2.64%
 1.24%
 1.36%
 1.58%
 2.05%
 1.7%
 2.1%
 3.69%
 10.06%
 71.15%Clear (daylight) street map image can be seen on geolist.org.
Map coordinates:
43° 53' 30.2" North, 3° 55' 24.8" West
43° 22' 58.3" North, 3° 13' 13.5" West
42° 52' 10.8" North, 2° 31' 2.3" West
Some cities around Castro-Urdiales sort by population:
• Algorta
		17.5 km =10.9 mi, 
102°
• Getxo
		17.1 km =10.6 mi, 
99°
• Portugalete
		17.6 km =10.9 mi, 
113°
• Santurtzi
		16.4 km =10.2 mi, 
111°
• Laredo
		16.1 km =10 mi, 
280°
• Zierbena
		11.7 km =7.3 mi, 
108°
• Ortuella
		15.5 km =9.6 mi, 
120°
• Zalla
		18.1 km =11.2 mi, 
157°
Sources (retrieved 2019-11-25):
» Earth at Night: Flat Maps 2012, 2016