Ambient lighting provides overall illumination and is meant to create a general and uniform lighting level. It's the first layer of lighting and sets the tone of a space. That's why it's typically soft or diffuse, and often dimmable to accommodate day and nighttime settings.
An ambient lighting source should consist of warm lighting with enough lumens (brightness) to make everything in the room visible. Warm color temperatures help give the room a tranquil ambiance that's as inviting as it is comforting.