Past perfect continuous vs past continuous/past perfect

[cinnamonroll]

Hi!

Would anyone be able to help me out on the differences in the below sentences?

1. It had been snowing when I built a snowman.
2. It was snowing when I built a snowman.


3. It had been snowing.
4. It had snowed.


Thank you :)

[Tukanja]

I'm not good enough to understand any of your sentences.
I wonder if you can get mine

5) It snowed for a long time before I started to build a snowman.
6) It was snowing while I was building a snowman.
7) I stopped building the snowman before I had made it, and took a walk with my dog.
8) I patted the dog which had been wandering with me since I had stopped building the snowman.
9) At length, I finished the snowman which I'd started to build yesterday.