Why does cold water flow below warm water?

• A. Cold water has a lower density
• B. Cold water has a higher density
• C. Cold water has lower pressure
• D. Cold water has higher pressure

Answer: (B)

Density dictates how water behaves when layers meet. Warmer water is less dense and tends to rise, while colder water is more dense and tends to sink. That difference in density creates buoyancy: the denser, cold water moves downward and settles below the warmer, lighter water. So the reason cold water flows below warm water is because it has a higher density. Pressure differences aren’t the primary cause of this vertical arrangement.