SI
SI
discoversearch

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor.  We ask that you disable ad blocking while on Silicon Investor in the best interests of our community.  If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.
Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?


To: Brumar89 who wrote (889843)9/24/2015 5:55:49 PM
From: J_F_Shepard  Read Replies (1) | Respond to of 1574404
 
Where do you think this data came from? You ever read "Hunt for Red October" by Tom Clancy

en.wikipedia.org

Oceans
For the use of ocean thermoclines to generate energy, see Ocean thermal energy conversion.




Graph showing a tropical ocean thermocline (depth vs. temperature). Note the rapid change between 100 and 1000 meters. The temperature is nearly constant after 1500 meters depth.






Graph of different thermoclines (depth vs. latitude) based on seasons and latitude


Most of the heat energy of sunlight is absorbed in the first few centimeters at the ocean's surface, which heats during the day and cools at night as heat energy is lost to space by radiation. Waves mix the water near the surface layer and distribute heat to deeper water such that the temperature may be relatively uniform in the upper 100 m (300 ft), depending on wave strength and the existence of surface turbulence caused by currents. Below this mixed layer, the temperature remains relatively stable over day/night cycles. The temperature of the deep ocean drops gradually with depth. As saline water does not freeze until it reaches -2.3 °C (colder as depth and pressure increase) the temperature well below the surface is usually not far from zero degrees. [1]

The thermocline varies in depth. It is semi-permanent in the tropics, variable in temperate regions (often deepest during the summer) and shallow to nonexistent in the polar regions, where the water column is cold from the surface to the bottom. A layer of sea ice will act as an insulation blanket.

In the open ocean, the thermocline is characterized by a negative sound speed gradient, making the thermocline important in submarine warfare because it can reflect active sonar and other acoustic signals. Technically, this effect stems from a discontinuity in the acoustic impedance of water created by the sudden change in density.

When scuba diving, a thermocline where water drops in temperature by a few degrees Celsius quite suddenly can sometimes be observed between two bodies of water, for example where colder upwelling water runs into a surface layer of warmer water. It gives the water an appearance of wrinkled glass that is often used to obscure bathroom windows and is caused by the altered refractive index of the cold or warm water column. These same schlieren can be observed when hot air rises off the tarmac at airports or desert roads and is the cause of mirages.

Other water bodies 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 the warm water is exposed to the sun during the day, a stable system exists and very little mixing of warm water and cold water occurs, particularly in calm weather.

One result of this stability is that as the summer wears on, there is less and less oxygen below the thermocline as the water below the thermocline never circulates to the surface and organisms in the water deplete the available oxygen. As winter approaches, the temperature of the surface water will drop as nighttime cooling dominates heat transfer. A point is reached where the density of the cooling surface water becomes greater than the density of the deep water and overturning begins as the dense surface water moves down under the influence of gravity. This process is aided by wind or any other process (currents for example) that agitates the water. This effect also occurs in Arctic and Antarctic waters, bringing water to the surface which, although low in oxygen, is higher in nutrients than the original surface water. This enriching of surface nutrients may produce blooms of phytoplankton, making these areas productive.

As the temperature continues to drop, the water on the surface may get cold enough to freeze and the lake/ocean begins to ice over. A new thermocline develops where the densest water (4 °C) sinks to the bottom, and the less dense water (water that is approaching the freezing point) rises to the top. Once this new stratification establishes itself, it lasts until the water warms enough for the 'spring turnover,' which occurs after the ice melts and the surface water temperature rises to 4 °C. During this transition, a thermal bar may develop.

Waves can occur on the thermocline, causing the depth of the thermocline as measured at a single location to oscillate (usually as a form of seiche). Alternately, the waves may be induced by flow over a raised bottom, producing a thermocline wave which does not change with time, but varies in depth as one moves into or against the flow.



To: Brumar89 who wrote (889843)9/24/2015 5:59:04 PM
From: J_F_Shepard  Read Replies (1) | Respond to of 1574404
 
Just one example.......

Occurrence of large temperature inversion in the thermohaline frontal zone at the Yellow Sea entrance in winter and its relation to advection
Authors

Temperature inversion (higher temperature at a deeper depth) in winter and its relation to advection were investigated by analyzing both conductivity-temperature-depth data in the southern Yellow Sea (YS) and northwestern East China Sea during the winter of 2002–2003 and time series data of temperature, salinity, and currents at a buoy station at the YS entrance. Significant temperature inversions occur predominantly along the thermohaline front at the YS entrance where the Cheju Warm Current Water (CWCW) and the cold coastal waters meet. In February 2003, on the northern frontal zone along 34°N where isotherms and isohalines declined downward to the north, particularly large inversions with temperature differences of larger than 2.0°C were observed to occur more in troughs than in the crests of the wave-like frontal meander where the cold Korean coastal water (KCW) advances farther southward. The inversion persisted until mid-April at the buoy station in the frontal zone, and both temperature and salinity showed simultaneous variations in the same manner. During episodic occurrences of large inversions, temperature and salinity decreased sharply in the upper layer, but increased concurrently in the lower layer. These episodic inversions were found to be closely related to the westward advection of the KCW in the upper layer and the northward advection of the CWCW in the lower layer. It is considered that these advections may play an important role in maintaining baroclinicity in the northern frontal zone, which is responsible for driving the westward transversal flow across the YS entrance.



CTD measurements used for the study. Squares and plus signs denote the CTD stations of the Korea Ocean Research and Development Institute (KORDI) and the Fisheries Research and Development Institute (NFRDI) of Korea, respectively. The diamond symbol denotes the mooring location of an ocean data buoy during February to September 2003.