Hello,
I have been looking at the transmission/reflection coefficients for liquid/solid interface as function of angle.
I saw mathematical derivations of these dependencies but there is something I can not grasp.
Why, at the first critical angle (when the refracted angle for L-waves is 90 degrees), is there a full reflection ?
Why at this angle we have a zero transmission coefficient also for the shear waves ?

I am seeking an intuitive explanation rather than a formula.