Since school years, everyone knows that water is denser than air. Because of this, the change in pressure under water with immersion occurs faster than its change with increasing height. So, when descending 10 meters, there is an increase in pressure on one atmosphere. In deep oceanic depressions reaching 10 thousand meters, this figure is 1 thousand atmospheres. How to find out how pressure under water changes and how it affects living things will be described below.
Physical calculations
The density of salt water is 1-2% higher than fresh water. Therefore, with a certain accuracy, you can calculate what pressure is under water, because when you dive for every 10 meters, it grows by one atmosphere. For example, a submarine at a depth of 100 meters experiences a pressure of 10 atmospheres, which can be compared with the performance inside a steam boiler in a steam locomotive. From this it follows that each layer in the sea corresponds to its own hydrostatic indicator. All submarines are equipped with manometers that measure the water pressure overboard, on the basis of which you can determine the degree of immersion.
At great depths, the compressibility of water becomes noticeable, since its density in the deeper layers is higher than on the surface. And the pressure rises faster than linearly, which is why the graph deviates slightly from a straight line. The additional pressure caused by the compression of the liquid increases in proportion to the square. When descending 11 km, it makes up about 3% of the total pressure at this depth.
How to explore the seas and oceans
In the study, bathyscaphes and bathyspheres are used. A bathysphere is a steel ball with a void inside that withstands the very high pressure of the deep sea. A porthole is placed in the wall of the bathysphere - an airtight hole closed by durable glass. The bathysphere with the researcher is lowered from the ship on a steel cable to that layer of water that the spotlight cannot illuminate. Thanks to this device, it was possible to go down to 1 km. Bathyscaphe with a bathysphere (reinforced at the bottom by a large steel tank), which is filled with gasoline, can achieve even greater immersion.
Since the density of gasoline is less than water, such a design can move into the sea, like an airship in the air. Instead of light gas, gasoline is used. At the same time, the bathyscaphe is equipped with a reserve of ballast and an engine, thanks to which, unlike the bathysphere, it can move independently, without requiring communication with the ship on the surface.
Pressure studies underwater at depth
At first, the bathyscaphe floats in the water, like a floating submarine spoon. To start diving, seawater flows into empty ballast compartments, because of which the structure begins to sink deeper and deeper under water until it reaches the bottom. To ascend to the surface, ballast discharge is performed, and without excess load, the bathyscaphe easily rises to the surface.
The deepest diving using the bathyscaphe was performed on January 23, 1960, when he spent 20 minutes in the Mariana Trench at a depth of 10,919 meters under water, where the pressure was more than 1,150 atmospheres (the calculation was carried out taking into account the increase in fluid density due to compression and salinity). According to the results of the experiment, researchers found living creatures that live even in such inaccessible places.
Water pressure
When diving, a diver or swimmer is faced with hydrostatic pressure over the entire surface of the body, while it exceeds the normal parameters of his body. Although the diver’s body may not be in direct contact with the water due to the rubber suit, it faces the same pressure that affects the swimmer’s body, as the air in the suit needs to be compressed in relation to the environment. Because of this, even the breathing air supplied through the hose must be pumped taking into account the water pressure at the intended depth. The same indicator must be in the air delivered from the cylinders to the scuba diver's mask. Thus, divers have to breathe air with unusual indicators.
A diving bell or caisson will not help from pressure, since air should be compressed in it so that it does not fall under the bell, that is, increased to environmental indicators. For this reason, during gradual immersion, there is a constant pumping of air with the expectation of water pressure at the reached depth.
High rates badly affect the well-being and health of a person, because of which there is a certain limit to which people can work without harm to health. Usually, when diving in a diving suit, it reaches 40 meters, which corresponds to 4 atmospheres. A diver can go down to a great depth only in a hard suit, which will take on the pressure of the water. It can be safely immersed up to 200 meters.
Impact on human health
If you are under water for a long time at high pressure, a considerable amount of air will dissolve in the blood and other body fluids. If a diver quickly rises to the surface, then dissolved air will begin to be released from the blood in the form of bubbles. Abrupt discharge of vesicles can lead to severe pain throughout the body and can lead to decompression sickness. Therefore, raising a diver who has worked for a long time at great depths can take a lot of time (several hours) so that the dissolved gas is released gradually and without bubbles.
Sea pressure and marine animals
Although huge values of the pressure occurring at the bottom of the sea were previously indicated, for marine animals these are not so significant indicators. Local residents can easily and calmly tolerate the huge fluctuations of this indicator. However, some of these animals do not tolerate a sharp change in pressure. For example, when removed to land, sea bass will swell, especially if it is removed very quickly from the water.
Atmospheric pressure under water is quite easy to calculate. It is enough to remember that for every 10 meters there is 1 atmosphere. However, at greater depths, other indicators come into force, such as compression and water density. In this connection, it is necessary to carry out the calculation taking into account these values.