Final answer:
Density currents are caused due to differences in water density and the buoyant forces caused by temperature differences in ocean currents and large-scale atmospheric circulation.
Step-by-step explanation:
Density currents are caused due to two reasons:
- The density of water at the two ends of the pool is different. When the temperature of water changes, the density of water also changes. For example, if the temperature of one end of the pool is higher than the other end, the water at the hot end becomes less dense and rises, while the water at the cold end is denser and sinks, creating a density current.
- Ocean currents and large-scale atmospheric circulation, which result from the buoyancy of warm air and water, can also create density currents. The buoyant forces caused by temperature differences drive the flow of fluids. For example, warm air from the tropics rises towards the poles, while cold air from the poles sinks towards the tropics, creating density currents.