Chapter 4

• Solar constant


  The solar radiation reaching the top of the atmosphere (in unit area and unit time)
• Laminar flow


  • Smooth, even flow, where the fluid moves in parallel layers and there is a minimal amount of mixing between layers
• Turbulent flow


  • Chaotic movement, where the fluid contains swirling regions called EDDIES and there is significant mixing of the fluid
• Holomictic lakes


  Lakes that undergo complete mixing from top to bottom at least once a year, typically during the spring and fall turnovers
• Types of holomictic lakes


  • Polymictic (mixing many times annually)
  • Cold monomictic (mixing once annually; exhibiting negative stratification)
  • Warm monomictic (mixing once annually; exhibiting positive stratification)
  • Dimictic (mixing twice annually)
  • Oligomictic (mixing less than once annually)
• Meromictic lakes


  Lakes that do not undergo complete mixing of their water column annually
• Amictic lakes


  The coldest lakes, are covered in ice permanently, and as such do not experience any circulation
• Destratification


  The process of disrupting thermal layers or chemical layers in a body of water, particularly in lakes and reservoirs
• Types of destratifiers


  • Air injection
  • Mechanical axial flow pumps
• Thermal stratification


  • Temperature layering
  • Seasonal variations
  • Ecological impact
  • Nutrient cycling
• Destratification


  • Mixing of layers
  • Nutrient redistribution
  • Temperature equalization
• Cold monomictic lakes


  Lakes with ice covering the surface most of the year, without ice during the summer, but with temperatures that never exceed 4ºC
• Cold polymictic lakes


  Lakes covered with ice for part of the year, without ice during the summer, with temperatures above 4ºC and stratified at least during the day
• Discontinuous cold polymictic lakes


  Lakes covered with ice for part of the year, free of ice above 4ºC, stratified during the summer, but with interruption of stratification and total circulation at irregular intervals
• Dimictic lakes


  Lakes covered with ice for part of year, stratified during the summer, with circulation during periods of transition between these two states of vertical organization
• Warm monomictic lakes


  No ice cover at any time of the year, stable stratification during part of the year and vertical mixing during one period of the year