Density is how close together the molecules of a substance are or how much mass a substance has in a given space. The closer the molecules- the more dense something is. The further apart the molecules- the less dense something is.
Cold water- the molecules are closer together. So, cold water is more dense and heavier. Warm water- the molecules are further apart. So, warm water is less dense and not as heavy.
Because cold water is more dense, it is heavier and sinks. Because warm water is less dense, it is lighter and moves to the surface of the ocean or the arctic poles.
When the warm water reaches where it is colder (either the surface of the water or the arctic poles) it cools down (becomes colder) and becomes more dense and moves toward the the ocean floor or the Equator where it is warmer.
When the cold water reaches the the ocean floor or the equator it is warmed and becomes less dense and rises toward the surface or the arctic poles again. This rising and falling of water creates a current- convection current! This is called an ocean current !!!!!!!!
Where are two places that water in the ocean can go?
1. The equator and the arctic poles
2. Surface of the ocean and the ocean floor