Need help interpreting GB's battery use graph and colors!!

[taylormah]

I am learning to interpret the battery use screen to better manage my device's battery life. Most of the things are self explanatory, but I have three things that I dont understand.

-On the graph screen, what is the difference between time on top and bottom of the graph?

-What do the colors mean on the phone signal bar? I understand black is airplane mode, red means no signal, but what do green, bright yellow, light yellow and gray mean? Today was the first time that I noticed green and bright yellow (as shown in the attached image), otherwise it always stayed on light yellow and gray. What does it mean?

-On the battery use display, what is the blue bar below the little graph on the top of the screen?

 

[Snow02]

The one you circled in pink is just a small version of the blown up graph.

As far as signal goes, green is the strongest. I think then it's yellow. Then gray. Then red. This is important because the weaker the signal, the worse your battery life will be.