Answer:
Sundial is an instrument showing the time by the shadow of a pointer cast by the sun on to a plate marked with the hours of the day.
If you mean climate change. Then scientists can study it by seeing where places and things are eroded.
Refraction is the change in direction of waves that occurs when waves travel from one medium to another. Refraction is always accompanied by a wavelength and speed change. Diffraction is the bending of waves around obstacles and openings.
Change in position of object = Displacment