I find the CK pretty dark to see well is there any tool to increase brightness of the land? IF I turn on Sky it becomes all foggy and blueish , if I turhn on light it coms out the shadows that make things worst .. any other way?

You do mean in exteriors, right?

You can change the time of day in the preferences menu. There's something called "Bright Light Color" there too, which I have no idea what it does.

And finally, make sure that your worldspace (if you are working on a custom one) has a climate or weather enabled.

Unless you're working with lighting, toggling lighting will make everything brighter so you can see what you're doing.

If you are working with lighting, you should be placing lights in your space to make dark places brighter.

The one other place you could look for what you want is in the cell's ambient lighting settings.