BIO-8 Lecture Notes - Lecture 30: Temperate Climate, Hypolimnion, Epilimnion
Document Summary
Most variations in lake trophic status: substrate, areas where run-off through natural vegetation has eroded sedimentary rock. From seasonal temperature variation and density profile of water, leads to general thermal profile. Warm water at a lower density than cold water, so the warm water floats on top of the cold water. Surface layer exposed to atmosphere, absorbs warmth and oxygen in the summer. If the temperature and density difference is great enough then a lake will stop mixing and become stratified: epilimnion: upper, warmer layer, thermocline: temperature drops off steeply, hypolimnion: lower, cold layer. In the beginning of winter: surface temperature begins to dissipate into the atmosphere, surface layer beginning to have similar temperature and density profile similar to hypolimnion. Eventually thermal stratification will break down because there is no density profile to maintain it. Lakes begin to turn over vertically (fall turn over) where surface water goes deep- and deep-water surfaces.
