The dominance of the cool makes the warm stand out.
The difference between the cooler and the warmer areas can be more subtle, like the relative temperatures in the scene, below, and still bring our attention to the portion of the image that is not dominant:
For homework, find an image you like and make a painting where you change the colors so that either the warms or the cools take up most of the total area. You can use one of the following images, or find one on your own.
You could cool down all this green and make the boat orange. Or make the trees and grass and water much more yellow and paint the boat blue. Or both!
Can you think of a way to leave the boat blue and change everything else?
What if you made the rocks rustier and changed the trees to Golden yellow fall cottonwoods? Then you could use more blue in the water and change the sky to sunset.