Light on Rainy Days

After one of the sunniest Aprils ever here in Wisconsin, we are now
slated for a good week of solid rain and overcast. What I wonder is
how much light still comes through that my plants will be able to make
use of? Obviously, it's not golden sunlight, but do enough of the
wavelengths that stimulate photosynthesis and growth still make their
way through the cloud cover and rain? Or will my plants just sort of
enter semi-dormancy until Mr. Sun pokes his head out again?

viv
.