This popped up in the Random Idea and I'm glad I got to see it. Yes, the angle of the sun does play a huge role on the intensity. We live in Calgary (Latitude 51.12; Longitude -114.01) and have a farm 524 KM (326 Miles) NE of Calgary (54.42 Latitude; -110.27 Longitude). In the summer, the sun rises in the NE and sets really low in the NW and mid day is practically straight up, giving us very long days. Plants, like petunias, do perform much differently. My Mom lives near our farm and her petunias are more floras, bigger and will do well in East facing locations.
At the Farm: Summer Solstice (17 hours 14 minutes daylight)
Sunrise: 4:45AM (Twilight at 3:49AM)
Sunset: 10:00PM (Twilight at 10:56PM) You can golf until almost 11PM!
In Calgary: Summer Solstice (16 hours 34 minutes daylight)
Sunrise: 5:20AM (Twilight at 4:33AM)
Sunset: 9:55PM (Twilight at 10:46PM)
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At the Farm: Winter Solstice (7 hours 17 minutes daylight)
Sunrise: 8:40AM (Twilight at 7:56AM)
Sunset: 3:58PM (Twilight at 4:42PM) It's dark early!!
In Calgary: Winter Solstice (7 hours 53 minutes daylight)
Sunrise: 8:37AM (Twilight at 7:57AM)
Sunset: 4:31PM (Twilight at 5:11PM)
I start my greenhouse in Mid March when the days become near 12 hours daylight.
Here's a photo of how the lighting looks with a low setting sun( taken at 8:30PM on June 26th vs. 6:15 PM)
