Since school years, everyone knows that water is denser than air. Because of this, the change in pressure under water with immersion is faster than its change with increasing altitude. So, when descending 10 meters, there is an increase in pressure per atmosphere. In deep oceanic depressions, reaching 10 thousand meters, this figure is 1 thousand atmospheres. How to find out how pressure changes under water and how it affects living beings will be described below.
The density of s alty sea water is 1-2% higher than that of fresh liquid. Therefore, with a certain accuracy, it is possible to calculate what pressure is under water, because when immersed for every 10 meters, it increases 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 indicators inside a steam boiler in a locomotive. It follows from this that each layer in the sea has its ownhydrostatic index. All submarines are equipped with pressure gauges that measure the pressure of the water overboard, based on which you can determine the degree of immersion.
At great depth, the compressibility of water becomes noticeable, since its density in deep layers is higher than on the surface. And the pressure rises faster than linearly, causing the graph to deviate slightly from a straight line. The additional pressure caused by fluid compression increases with the square. When descending 11 km, it is about 3% of the total pressure at this depth.
How seas and oceans are explored
The study uses bathyscaphes and bathyspheres. A bathysphere is a steel ball with a void inside that can withstand the very high pressure of the deep sea. A porthole is placed in the wall of the bathysphere - a hermetic hole closed with durable glass. The bathysphere with the researcher is lowered from the ship on a steel cable to that layer of water that the searchlight cannot illuminate. Thanks to this device, it was possible to go down to 1 km. Bathyscaphes with a bathysphere (reinforced at the bottom with a large steel tank), which is filled with gasoline, can achieve even greater immersion.
Because the density of gasoline is less than water, such a structure can move in the sea, like a blimp in the air. Gasoline is used instead of light gas. At the same time, the bathyscaphe is equipped with a supply of ballast and an engine, thanks to which, unlike the bathysphere, it can move independently, without requiring communication with the ship onsurface.
Studies of pressure under water at depth
At first, the bathyscaphe floats on the water like a floating underwater spoon. To start diving, sea water is poured into the empty ballast compartments, due to which the structure begins to sink deeper and deeper under the water until it reaches the bottom. To ascend to the surface, the ballast is released, and without excess cargo, the bathyscaphe easily rises to the surface.
The deepest dive using a bathyscaphe was performed on January 23, 1960, when he spent 20 minutes in the Mariana Trench at a depth of 10919 meters under water, where the pressure was more than 1150 atmospheres (the calculation was carried out taking into account the increase in the density of the liquid due to compression and salinity). As a result of the experiment, the researchers found living creatures that live even in such hard-to-reach places.
When diving, a scuba diver or swimmer encounters 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, the diver's body is subject to the same pressure that affects the swimmer's body, since the air in the suit must be compressed to account for environmental factors. Because of this, even the breathing air supplied through the hose must be pumped in, taking into account the pressure of the water at the intended depth. The same indicator must be for the air delivered from the cylinders to the scuba diver's mask.Thus, divers have to breathe air with unusual rates.
A diving bell or a caisson will not help against pressure either, since the air in it should be compressed so that it does not fall under the bell, that is, increase it to environmental indicators. For this reason, during gradual immersion, there is a constant pumping of air with the expectation of water pressure at the depth reached.
High rates have a bad effect on the well-being and he alth of a person, which is why there is a certain limit to which people can work without harm to he alth. Usually, when diving in a diving suit, it reaches 40 meters, which corresponds to 4 atmospheres. A diver can descend to great depths only in a rigid space suit, which will take on the pressure of the water. It can safely dive up to 200 meters.
Impact on human he alth
When you stay under water for a long time at high pressure, a considerable amount of air will dissolve in the blood and other body fluids. If there is a rapid rise of the diver to the surface, then the dissolved air will begin to be released from the blood in the form of bubbles. The sudden release of bubbles can lead to severe pain throughout the body and lead to decompression sickness. Therefore, it may take a long time (several hours) for the dissolved gas to be released gradually and without bubbles to raise a diver who has worked at great depths for a long time.
Sea pressure and marine animals
Although the enormous values of pressure at the bottom of the sea were previously indicated, for marine animals these are not so significant indicators. Local residents can easily and calmly endure huge fluctuations in this indicator during the day. However, some such animals do not tolerate a sharp change in pressure very well. For example, sea bass will swell when taken to land, especially if taken out of the water very quickly.
Atmospheric pressure under water is fairly 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 play, such as compression and water density. In this connection, it will be necessary to carry out the calculation taking into account these values.