Final answer:
Colder, saltier water, which is denser, sinks in thermohaline circulation, contributing to a global circulation pattern crucial for heat distribution and climate regulation. In freshwater bodies, water at approximately 4°C sinks during seasonal turnovers.
Step-by-step explanation:
In thermohaline circulation, the type of water that sinks is colder and saltier water, which has a higher density. Water becomes denser in two ways: by cooling and by increasing in salinity. The denser water sinks beneath the lighter, fresher, or warmer water above, contributing to the global circulation pattern known as the thermohaline circulation. The freezing process near the poles generates this salty, dense water. As ice forms, salt is left behind in the surrounding water, making it saltier. This process, in combination with cold temperatures, increases the water's density, causing it to sink.
On a larger scale, this sinking water moves along the deep ocean, driving the global conveyor belt, which is crucial for regulating climate by distributing heat around the planet. Additionally, in freshwater bodies like lakes, water at approximately 4°C, which is the temperature of maximum density for fresh water, sinks to the bottom during seasonal turnovers. This yearly cycle ensures that nutrients from the bottom are mixed throughout the lake, aiding ecological balance within the freshwater environment.