Density gradients refer to the gradual change in density of a substance, often observed in fluids. This phenomenon occurs when different layers of a fluid have varying densities, typically due to temperature differences, salinity, or the presence of different substances. For example, in a body of water, warmer water is less dense than cooler water, leading to distinct layers. In scientific studies, density gradients are important for understanding processes like ocean circulation and atmospheric dynamics. They can also be utilized in laboratory techniques, such as centrifugation, where samples are separated based on their density differences, allowing for the analysis of various components.