why can't lightning come from nimbostratus clouds?

Answer 1

Good question. I believe the answer is because nimbostratus, meaning layed clouds which produce rain, are not clouds of vertical development. Stratus clouds are stable, meaning that if they are lifted they settle back to their original level. It takes clouds of vertical development, like cumulonimbus, to separate the electrical charges in a cloud which will subsequently discharge in a flash of cloud to cloud or cloud to ground or ground to cloud lightening