Weather Question

So, here's one for you weather experts, or you Canadians, either one...
Why is the area shown by the black arrow always have nearly unlimited visibility? I've been checking it out for quite a while now, and it's always clear in this one area. Now, I'm quite certain that this isn't some amazing weather phenomena that only occurs in north-western Canada, so I assume it's some sort of lack of any measurement of the visibility in this area. Does anyone know what the truth really is?

Why is the area shown by the black arrow always have nearly unlimited visibility? I've been checking it out for quite a while now, and it's always clear in this one area. Now, I'm quite certain that this isn't some amazing weather phenomena that only occurs in north-western Canada, so I assume it's some sort of lack of any measurement of the visibility in this area. Does anyone know what the truth really is?
