When I add a fill directional light to a scene, I notice you can't adjust the intensity other than change the color. But, what if I want it to be brighter than the default white color? Is there anyway to adjust it?

I suppose you could set it up in the atmosphere editor lighting panel so that the settings affect all lights, then adjust down from there. But just thought there might be another way.

i do,'t think there is another way with directionnal lights. Brightness can't be adjusted, only intensity can, by giving it a greyer colour.

Not exactly the best way to get a brighter infinite light source - copy and paste an exact duplicate of the original! 

I normally only do this when I'm using the other kinds of light and want to have a stonger volumetric smoke effect than you get with having a single brighter source in Vue.

If you want to reduce the intensity of a directional light, you will have to reduce the intensity of the color of that light.

That is, if your light is white, pick a shade of grey.

To increase it, you have to add a new light as suggested by impish.

Between these two tricks, you should be able to get the light intensity you need.

I find that a better effect can be achieved than by changing the colour to grey - instead, add a gel to the light and choose the plain grey material. You can then adjust the intensity by changing the darkness of the gel. This seems to have the desired effect without robbing the image of saturation.