This has a two word answer: sun's heat. The faster moving molecules near the ocean's surface are provided with enough energy from the sun to escape the surface they are near.
The 4 fourth row of the graph is a quadratic graph
According to the law of reflection, When a ray of light passes from rarer medium to denser medium , it bends towards the normal. So, if there is a transparent material that is more dense than glass then the ray of light will bend towards the normal. The direction of light through the medium is predicted by Snell's Law. According to the Snell's law:
n₁ sin θ₁ = n₂ sin θ₂
Where n₁ is the refractive index of the first medium
n₂ is the refractive index of second medium.
θ₁ and θ₂ are the angle of incidence of light in medium 1 and medium 2
