I am an artist that is looking for a lamp or bulb that reproduces the look of natural?

daylight (north light) to illuminate my subjects. This way I will not be at the mercy of when the daylight in my studio fades, and I can paint anytime with light that is constant and unchanging. My question is- is there a light bulb, fixture, or lamp that I can buy that reproduces the look of cool north daylight? So far, I have never seen any artificial light capable of this. It is simply too harsh, washed out, and opaque.