There is no end to the variability of light. Over the course of a day I popped a few shots of the TD Bank on Bridge Street in Frenchtown from the same location at different times of the day.
Bridge Street runs west-east and the bank is on the north side so it receives full sun for the better part of the day. I wanted to see how the light changes and looks in B&W. I took three shots, one in the morning, one in the afternoon and one after sunset.
The morning light was bright and rich giving me very beautiful whites, good grays and some deep blacks. It was a very clear day so there was no diffusion of the light by clouds. There was a lot of reflected light from the driveway up into the shade under the porch roof in the front of the building, softening the shadows. As a result, these shadow are much lighter than the shadowed street in the foreground which has no reflected light on it. Just light from the sky.
Later in the afternoon with the sun coming from a different direction the building took on a more 3 dimensional look. The shadows around the windows gave them some depth. Without reflected light, the shadows in the front of the building under the porch roof were darker and deeper. The street was a little lighter than in the morning most likely due to light reflecting off the face of the building. Light bouncing off the windows also can be seen shining on the street. Photos taken using sunlight reflected off window is a soft even light and is great for portraits.
After sunset I lost all the direct light. When the sun goes down it still shines on the sky above us and the sky becomes our primary light source. The sun is a miniscule light source compared to whole sky. The sun is light a giant spot light giving us sharp contrasty shadow whereas the sky is more like a blanket of light resulting in much softer shadows and less tonal contrast over all. Everything in a narrow range of grays.
The contrast is much lower and it doesn’t have the same snp as the other two but now we can see more detail in the highlights.
Time of day makes a big difference when photographing buildings. It may be full direct sun, angular sun or no sun plus everything in between. Buildings are fun to photograph and it important to pick the right time.
If you have a building in mind to photograph, plan ahead. Determine its orientation and decide how you would like to see the light on it. One of my favorite sites is called the Photographers Ephemeris which will show you the direction the sun is shining throughout the day. I use it often.