The colour usually deepens toward the zenith and also with the elevation of the observer.
The afternoon minimum at Kew gradually deepens as midsummer approaches.
Otherwise, when Beethoven has anything special for the violoncellos to say, he invariably softens and deepens their singularly incisive cantabile tones by doubling them with the violas.
As the main valley deepens, the tributary streambeds are deepened also, and gradually cut their way headwards, enlarging the area whence they draw their supplies.
During the process it deepens in colour.