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The driving force in stratification is gravity, which sorts adjacent arbitrary volumes of water by local density, operating on them by buoyancy and weight.A volume of water of lower density than the surroundings will have a resultant buoyant force lifting it upwards, and a volume with higher density will be pulled down by the weight which will be greater than the resultant buoyant forces ...
In particular, during periods of thermal stratification, gas exchange between the epilimnion and hypolimnion is limited by the density difference between these two layers. Consequently, decomposition of organic matter in the water column and sediments can cause oxygen concentrations to decline to the point of hypoxia (low oxygen) or anoxia (no ...
During periods of thermal stratification, water density gradients prevent oxygen-rich surface waters from mixing with deeper waters. Prolonged periods of stratification can result in the depletion of bottom-water dissolved oxygen; when dissolved oxygen concentrations are below 2 milligrams per liter, waters are considered hypoxic. [22]
Lake stratification is the tendency of lakes to form separate and distinct thermal layers during warm weather. Typically stratified lakes show three distinct layers: the epilimnion, comprising the top warm layer; the thermocline (or metalimnion), the middle layer, whose depth may change throughout the day; and the colder hypolimnion, extending to the floor of the lake.
Thermoclines can also be observed in lakes. In colder climates, this leads to a phenomenon called stratification. During the summer, warm water, which is less dense, will sit on top of colder, denser, deeper water with a thermocline separating them. The warm layer is called the epilimnion and the cold layer is called the hypolimnion. Because ...
In the water column, the epilimnion sits above all other layers. The epilimnion is only present in stratified lakes. On the topside of the epilimnion it is in contact with air, which leaves it open to wind action, which allows the water to experience turbulence. Turbulence and convection work together to make waves which increases aeration.
The development of thermal stratification during winter is then defined by two periods: Winter I and Winter II. [16] During the early winter period of Winter I the major heat flux is due to heat stored in sediment; during this period the lake heats up from beneath forming a deep layer of 4 °C water. [16]
Stable stratification of fluids occurs when each layer is less dense than the one below it. Unstable stratification is when each layer is denser than the one below it. Buoyancy forces tend to preserve stable stratification; the higher layers float on the lower ones. In unstable stratification, on the other hand, buoyancy forces cause convection ...