It certainly wouldn’t bend it up or down it would just be diffracted in all directions to the original vector of travel. As for the water on pavement, this is a very different phenomenon known as a inferior mirage, the explanation of how this happens first was explained by French mathematician Pierre de Fermat, who stated that the reason the light travels along these funny lines is due to temperature being higher and air density being lower at the level of the road. Without much thought this is not applicable to proper experimental conditions such as on a calm cold night on a lake with no warm temperature gradient at the surface. You see how this mirage example and the star light diffraction example is not relatable to this experiment?

What is whrong with this experiment, criticism is encouraged, please explain yours elf. It may prove you right that the earth is flat!!!