Why is the battery bar on my iPhone 5 white instead of green?

[iMore Question]

I know what it means if the battery bar is yellow . . but what does a white battery bar indicate?

 

[Tartarus]

why is the battery bar on my iphon5 white instead of green

Yellow is Battery Saving Mode
Green is Battery is currently Charging/connected to a power source
White is iPhone is using Battery as Power Source
Red is Battery level is below 20%