the closer you get to the equater i would think that the time for sun up/down would like not change throughout the year, and if it was a vegg lighting conditions you could grow monsters like that one above..... but how do you get it to flower...
Also i would think growing in alaska would be sick 24 hr. light half the year, and then 24 dark the other half, that would be sick to make some monsters aswell, but i think the sun just dose down and thats it, so again flowering the plant would be tricky.