3. water mass A is warm and saltier
4. water mass C is cold and less salty
5. water mas C is the densest
6. Water mass A is the least dense.
Explanation:
Before answering the questions, we will review some theoric about water masses and their distribution.
On the sea surface, density increases from the equator to the poles. In-depth, density increases from the surface to the bottom of the ocean. Density distribution in depth is controlled by temperature.
Water masses that are denser tend to sink faster than less dense water masses. Less dense water places above the denser water. The difference in density generates convective streams. Denser colder, and heavier water descends, while less dense, warmer, and lighter water ascends.
Vertical water motion in the ocean between the surface and the bottom is inhibited by the density contrast between the inferior layer and the superior one. However, in the poles, there is hardly any temperature variation between the surface and the bottom.
Cold and dense water masses come from the polar regions at higher latitudes. Different water masses can be differentiated from the surface to the bottom in the middle of the ocean.
Central water mass
It is in the central region of the ocean. It generates between the subtropical convergent zones. It might reach up to 1000 mt deep. This mass of water is the most saline one, and its temperature ranges from 8ºC to 25ºC. It is the most saline water because it is subjected to high evaporation.
Intermediate water mass: Antarctic
It is under the central water mass. It generates in the artic and antarctic convergent regions. The most extended one is the antarctic one, which is originated in the subantarctic superficial water. Its temperature ranges from 2ºC to 7ºC, and its salinity ranges from 34,1o/oo to 34,7o/oo.
Deep Arctic water mass
It is produced by the mixture of the high salinity water from the Gulf stream and the superficial subarctic water. These masses are in the Atlantic ocean. Its temperature ranges from 3 to 4ºC, and its salinity media is 34,9o/oo.
Deep Antarctic water mass
The densest water mass. Originated during the winter in the Antarctic region, but can be found up to 30ºN of latitude. Its temperature ranges from -1ºC to 0.5ºC, and its low salinity is approximately 34.7 o/oo. They are in the Pacific and Indic oceans.
In the exposed image, we can identify
the X ax → Latitude → 0º is the Equatorthe Y ax → Depth
A) This is the most superficial one, and is well-placed from the equator to the subtropics. More or less 40º latitude north and south. This mass is probably the central mass, which is the most saline due to the high evaporation rate, and the warmest. It is almost 1000 mt deep.
Question: what are two likely characteristics of water mass A in the diagram above?
3a. warm or cold
3b. less or more salty
Water mass A is warm and saltier.
B) This mass is coming from the north pole. At high latitudes, there is little variation of temperature between the superficial region and the deep region. It is placed under mass A. It is colder than A, and less saline.
C) This is the densest mass, coming from the south pole. A little variation of temperature between the superficial region and the deep region. It reaches up to 25º north in latitude, approximately.
Question: What are two likely characteristics of water mass C in the diagram above?
4a. warm or cold
4b. less or more salty
Water mass C is cold and less salty.
Question: which water mass is most dense?
A, B, or C
Remember that density increases from the equator to the poles, and from the surface to the bottom. So, the densest mass is C.
Question: which water mass is least dense?
A, B, or C
The same reasoning as before. Mass A is the most superficial one and between the subtropics, making it the densest mass of water.
