Six Forces That Drive Ocean Currents

1. Wind – Surface friction drags water; prevailing winds (trade winds, westerlies) set major gyres in motion.
2. Coriolis Effect – Earth’s rotation deflects moving water right (NH) / left (SH), shaping circular gyres.
3. Temperature & Salinity (Density) – Cold/salty water sinks; warm/fresh water rises, driving thermohaline circulation.
4. Earth’s Rotation (Equatorial Bulge) – Centrifugal force piles water at equator, creating pressure gradients poleward.
5. Bottom Topography – Ridges, seamounts, and continental slopes steer, block, or accelerate deep flows.
6. Tides – Lunar/solar gravitational pull generates tidal currents, especially in shallow seas and straits.

These factors interact non‑linearly, producing the complex global conveyor belt.