Can anyone explain

why the sky is always lighter inside a rainbow?
Terrible stormy day but I did manage to plant a whole load of winter vegetables when the howling wind finally ceased. I do hope the mice, slugs, deer or any other thieves don't get to eat them before we do! Quite likely as we are over run with mice and voles in the garden, luckily not in the house. They try to move in once it gets colder and have been spotted scampering up the outside walls of the house.
Do any of you brilliant ingenious photographers have any ideas how to discourage them from living in our garden?!