If the salinity of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation--- conversion of liquid water to water vapor. In this manner the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff.
Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.
A third process by which salinity may be altered is associated with the formation and melting of sea ice. When sea water is frozen, the dissolved materials are left behind. In this manner, sea water directly materials are left behind. In this manner, sea water directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water.
In the Weddell Sea Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.
2016高考英语(人教版)一轮题库:Book 7 Unit 2《Robots》
2016高考英语(人教版)一轮题库:Book 7 Unit 5《Travelling abroad》
2016高考英语(人教版)一轮题库:Book 5 Unit 4《Making the news》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解 2
2016高考英语(人教版)一轮题库:Book 6 Unit 3《A healthy life》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解 5
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解及书面表达 (7)
2016届高三英语一轮复习讲义:Book 1 unit 2
2016届高三英语一轮复习讲义:Book 1 unit 3
2016高考英语(人教版)一轮题库:Book 6 Unit 5《The power of nature》
2016高考英语(人教版)一轮题库:Book 8 Unit 2《Cloning》
2016高考英语(人教版)一轮题库:Book 7 Unit 3《Under the sea》
2016高考英语(人教版)一轮题库:Book 7 Unit 4《Sharing》
2016高考英语(人教版)一轮题库:Book 4 Unit 5《Theme parks》
2016高考英语(人教版)一轮题库:Book 6 Unit 4《Global warming》
2016高考英语(人教版)一轮题库:Book 8 Unit 5《Meeting your ancestors》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解 3
2016高考英语(人教版)一轮题库:Book 5 Unit 1《Great scientists》
2016高考英语(人教版)一轮题库:Book 6 Unit 1《Art》
2016高考英语(人教版)一轮题库:Book 4 Unit 3《A taste of English humour》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解及书面表达 (5)
2016届高三英语一轮复习讲义:Book 2 Unit 4
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解及书面表达 (4)
2016高考英语(人教版)一轮题库:Book 8 Unit 1《A land of diversity》
2016高考英语(人教版)一轮题库:Book 3 Unit 4《Astronomy:the science of the stars》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解及书面表达 (3)
2016届高三英语一轮复习讲义:Book 2 Unit 5
2017届高考英语复习冲刺阶段经典讲义系列语法突破介词
2016高考英语(人教版)一轮题库:Book 8 Unit 3《Inventors and inventions》
2017届高考英语复习冲刺阶段经典讲义系列突破阅读理解及书面表达 (6)
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