Anonymous asked: Hi Ms Cheong, I know that the plates move because of convection currents below, but why do the convection currents move in different directions in the first place? Thank you.
Source: http://dreamtigers.files.wordpress.com/2011/05/convection_currents_2final.jpg
When a liquid, solid, or gas gets heated, it expands. The expanded material, being less dense, rises, while colder, denser material sinks.
