I’ve seen rainbows below the horizon before – from aircraft they can be complete circles – but until last weekend I’d not seen one below the horizon while sitting in a car.
Driving up the M1, afternoon rain was easing but hanging in the air, being stirred up by the traffic. As the fine droplets swirled behind the cars sweeping past in the fast lane, brilliant rainbows swept across my field of view, apparently intersecting my car at opposite wheels.
The effect persisted every time a car passed, for about ten miles. Beautiful.