I think your shadow information is irrelevant...can you explain it further?
So far they have been gut feelings. Since my last post, I have been pondering how to get a more precise fix on the latitude of WTHAI1.
For WTHAI 4, I knew it must be about 10 am when the picture was taken because the shadow was almost directly below the fluffy white clouds that typically float at least 1000-2000ft (300-580m) above the surface. Despite this, the shadow is only slightly north of the clouds. That tells me it is near the equator. However, because it is near the equator, I can not tell the season based on the vegetation.
Up here at 55 degrees north, the ground is brown/white in the winter (Google has used winter images in the past). Not knowing the season is a major source of error since the Earth is tilted on its axis about 22.5 degrees. That means even
if I correctly guage the angle of elevation of the sun, the corresponding Latitude can vary by up to 43 degrees.
For WTHAI1, the long shadows hint at a location close to the poles. The green deciduous trees indicate that it is summer (and not
too close to the poles). This means I have the potential to narrow the angle of elevation to within 22 degrees: if I can just measure the angle of elevation of the sun. I can probably determine the time the picture was taken within about 30 minutes (Standard local time). For example, WTHAI1 was taken at
12:30 1300 (Correction: sundials are 24 hour clocks...). The length of the shadow varies throughout the day. It is longest at either midnight or sunrise/sunset; shortest at noon.
The difficulty is that to determine the angle of the sun from objects on the ground, I have to know how tall those objects are. Trees are tricky because their height changes based of how far north they are, as well as with how much water they get. I am assuming that the pictures are taken from directly overhead. This will be true for aerial photos, and likely many of the satellite photos.
Even if I determine how tall an object on the ground is, I still don't know when sunrise is... because I don't know the latitude (or exact day). I have yet to deterime if I can solve a series of equations (with a least 2 unknowns) for elevation of the light source.
TL;DR: I can determine the hemisphere (North vs South) with a high degree of certainty. Other than that, I may be just guessing using other visual cues. Generally, the closer to the poles you go, the longer the shadows at high noon.