What causes overturn in freshwater lakes? What will be an ideal response?
Freshwater has a maximum density at 4?C. During the summer, surface waters are warmer and less
dense than water at depth. The water of a lake will commonly be layered above and below a boundary
called the thermocline. Cooling of surface water during the winter will cause it to become denser than
underlying water, which weakens the thermocline and causes gravitational instability. The cold surface
water will tend to sink under these conditions, thereby stirring the lake in what is called overturn. This
has the benefit of oxygenating the deep-water layer and preventing it from becoming stagnant.
You might also like to view...
The international division of labor is based on complementarity
Indicate whether this statement is true or false.
Someone has offered you shares in a sure-shot wildcat oil-drilling venture in the Sierra Nevada of
California. Which of the following is the most important reason you should reject his shady offer? a. The Sierra Nevada is composed of granitic and metamorphic rocks. b. There is no prior oil or gas production in California. c. Drilling is prohibited in the entire Sierra Nevada because it is all national forest. d. Oil and gas production only occurs at present day plate boundaries. e. Movement along the San Andreas fault has caused all existing oil to leak to the surface.
Differences in emissivity of a substance are governed by differences in
A) moisture. B) pressure. C) temperature. D) wind speed.
____ ecosystems seem to be particularly sensitive to changes in acidity
a. Freshwater b. Marine c. Forest d. Grassland e. Alpine