What are some factors that affect the density of water?

When water cools, it causes the molecules to move closer together as they slow down. This slowdown of the molecules causes the water to become denser. The opposite happens as water heats up. As the temperature of the water rises, the molecules speed up and begin moving farther away from one another. read more

Salinity also plays a part in the density of water. Water that contains salt is much denser than water that does not contain salt. The more salt in the water, the denser it becomes. Scientists define density as the measure of mass per volume of liquid. The equation for calculating density is d = m / v. read more

Water vapor weighs less than the Nitrogen or Oxygen molecules that make up the rest of the air. And, water vapor takes up about the same amount of space. So, when you have more water vapor in the air, the air has less mass - which means it's less dense. read more

"The density of a material is given in units of mass per unit volume and expressed in kilograms per cubic metre in the SI system of units. In oceanography the density of seawater has been expressed historically in grams per cubic centimetre. The density of seawater is a function of temperature, salinity, and pressure. read more