When is day-time for the purpose of vampirism('s Weakness to Sunlight)?

Question

While outside during the day, health, magicka, and stamina are reduced, and the regeneration for each of these stats is reduced by 100%. The reduction increases with each stage of vampirism.

http://www.uesp.net/wiki/Skyrim:Vampirism#Weakness_to_Sunlight

What time has sunlight?

Answer 1

Day begins at 5am and ends at 7pm regardless of weather or the visibility of the sun.

http://www.uesp.net/wiki/Skyrim:Vampirism#Weakness_to_Sunlight

That makes 14 hours of sunlight; 10 hours of night-time.