The total mass of all waters of the oceans is divided by experts into two types - surface and deep. However, this separation is very conditional. A more detailed categorization includes the following several groups, distinguished by territorial location.
Definition
To begin with, we will give a definition of what water masses are. In geography, this designation refers to a sufficiently large volume of water that is formed in a particular part of the ocean. Water masses differ from each other in a number of characteristics: salinity, temperature, as well as density and transparency. Differences are also expressed in the amount of oxygen, the presence of living organisms. We have defined what water masses are. Now you need to consider their various types.
Surface water
Surface waters are those zones where their thermal and dynamic interaction with air occurs most actively. In accordance with the climatic features inherent in certain zones, they are divided into separate categories: equatorial, tropical, subtropical, polar, subpolar. Pupils who collect information to answer the question of what water masses need to know about the depth of their occurrence. Otherwise, the answer to the geography lesson will be incomplete.
Surface water reaches a depth of 200-250 m. Their temperature often changes, since they are formed by water due to atmospheric precipitation. Waves are formed in the thickness of surface water, as well as horizontal ocean currents. It is here that the largest number of fish and plankton are found. Between the surface and deep masses is a layer of intermediate water masses. The depth of their location is from 500 to 1000 m. They are formed in areas of high salinity and a high level of evaporation.
Deep water masses
The lower boundary of deep waters can sometimes reach 5000 m. This type of water masses most often occurs in tropical latitudes. They are formed under the influence of surface and intermediate waters. Those who are interested in what water masses are, and what are the features of their various types, it is also important to have an idea about the speed of the current in the ocean. Deep water masses move very slowly in the vertical direction, however, their horizontal speed can be up to 28 km per hour. The next layer is the bottom water masses. They are located at depths of over 5000 m. This type is characterized by a constant level of salinity, as well as a high level of density.
Equatorial water masses
“What are water masses and their types” - this is one of the compulsory topics of the course of a comprehensive school. The student needs to know that the waters can be assigned to a particular group not only depending on their depth, but also on the territorial location. The first type mentioned in accordance with this classification is the equatorial water masses. They are characterized by high temperature (reaches 28 ° C), low density, low oxygen content. The salinity of such waters is low. Above the equatorial waters is a belt of low atmospheric pressure.
Tropical water masses
They are also quite well warmed up, and their temperature does not change during different seasons by more than 4 ° C. Great influence on this type of water has ocean currents. Their salinity is higher, since a zone of high atmospheric pressure is established in this climate zone, and very little precipitation occurs.
Moderate water masses
The salinity level of these waters is lower than that of others, because they have a desalinating effect of rainfall, river, icebergs. In seasons, the temperature of water masses of this type can vary up to 10 ° . However, the change of seasons occurs much later than on the mainland. Moderate waters vary depending on whether they are in the western or eastern parts of the ocean. The former, as a rule, are cold, and the latter are warmer due to the warming of the internal currents.
Polar water masses
What are the coldest water masses? Obviously, they are those located in the Arctic and off the coast of Antarctica. With the help of currents, they can be carried to temperate and tropical areas. The main feature of the polar masses of water are floating blocks of ice and vast ice spaces. Their salinity is extremely low. In the southern hemisphere, sea ice passes into the region of temperate latitudes much more often than it does in the north.
Formation Methods
Pupils who are interested in what water masses will be interested in will also find out information about their education. The main method of their formation is convection, or mixing. As a result of mixing, the water plunges to a considerable depth, where vertical stability is again achieved. Such a process can occur in several stages, and the depth of convective mixing can reach up to 3-4 km. The next method is subduction, or "diving." With this method of mass formation, water is lowered due to the combined action of wind and surface cooling.