Automatic Changing Ambiance and Radiance Script

I really like the two new Ubuntu themes (Ambiance and Radiance) and I for once can't decide which one to use. So to use them both, I've modified the script created for New Wave Chronos to use the Radiance theme from 6 A.M. to 5 P.M. and Ambiance from 5 P.M. to 6 A.M.