There are many threads on this topic (like this one) but one aspect about the equation $ v = \lambda\nu $ still confuses me.
I have read that frequency does not change when light crosses into different media. But since light traveling in any media has a slower speed than light traveling in a vacuum, clearly the wavelength $ \lambda $ must be reduced in order to satisfy the above equation.
My question is: how can frequency remain constant while wavelength decreases?
The equation $ v = \lambda \nu $ suggests that wavelength and frequency are inversely proportional, so if one decreases, the other should increase. But when light crosses into a new medium, if wavelength changes but frequency doesn't, that seems to imply that the wavelength of light and frequency of light are unrelated.