In ocean water, the sun – rays provide heat by entering down to 25 meters depth. After this depth, the effect of sun’s radiation becomes negligible. Thus, due to insolation, the surface water of ocean becomes hotter. In polar regions, the cold water being heavy settles down at the bottom. Due to being light, the warm water of the equatorial regions flows towards the polar regions by surface currents. In this way, the transmission of the temperature of oceanic water takes place.