nice pics!
I've had a think about it and i'll tell you why the rainbow is mainly red- the suns light at that time of day has a orange/red tint to it so instead of a normal rainbow during the day where the normal 'white' sunlight gets dispersed by the raindrops producing a full coloured rainbow, there is only really red/orange light shining on the said raindrops so the rainbow appears red
*science hat off*