What are wave speed decreases?

Wave speed decreases happen when waves slow down as they move from one place to another.

Imagine you're pushing a toy car on a smooth floor, it zooms along quickly. But if you push the same toy car onto a carpet, it moves more slowly because the carpet is bumpy and not as smooth. That’s like what happens with waves when they go from one surface to another.

If waves are moving through water and then enter a shallower part of the ocean, they slow down, just like your toy car on the carpet. This is because the water in shallow areas doesn’t move as freely as it does in deep water. The wave still keeps going forward, but its speed drops.

This slowing down can make waves bend or change direction, kind of like when you walk from a smooth floor to a carpet and your steps get shorter. This is why waves near the shore sometimes look bent, they're slowing down as they reach shallower water!