What occurs in water at 39.2 degrees Fahrenheit?

Water exhibits maximum density at 39.2 degrees Fahrenheit (4 degrees Celsius). This is a significant property of water, as it is the temperature at which water is most dense. As water cools and approaches this temperature, it becomes denser; however, as it cools further below this point, it starts to become less dense again. This unique characteristic of water is crucial for aquatic life, as it allows for stratification in bodies of water, which can affect temperature layers important for ecosystems.

In colder water, ice forms on the surface, creating insulation for aquatic life below. Thus, the understanding of water's density changes with temperature is vital for various applications in water treatment and management.