Water in the seas and oceans is very different from river and lake water. It is salty - and this determines many of its properties. The freezing point of sea water also depends on this factor. It does not equal 0 °C, as is the case with fresh water. To be covered with ice, the sea needs a stronger frost.

It is impossible to say unequivocally at what temperature sea water freezes, since this indicator depends on the degree of its salinity. In different places of the world ocean it is different.

The most salty is the Red Sea. Here the concentration of salt in the water reaches 41‰ (ppm). The least amount of salt in the waters of the Baltic Gulf is 5‰. In the Black Sea, this figure is 18‰, and in the Mediterranean - 26‰. The salinity of the Sea of ​​Azov is 12‰. And if we take the average, the salinity of the seas is 34.7‰.

The higher the salinity, the more the sea water must cool to become solid.

This is clearly seen from the table:

Salinity, ‰	Freezing point, °C	Salinity, ‰	Freezing point, °C
0 (fresh water)		20	-1,1
2	-0,1	22	-1,2
4	-0,2	24	-1,3
6	-0,3	26	-1,4
8	-0,4	28	-1,5
10	-0,5	30	-1,6
12	-0,6	32	-1,7
14	-0,8	35	-1,9
16	-0,9	37	-2,0
18	-1,0	39	-2,1

Where the salinity is even higher, as, for example, in Lake Sivash (100 ‰), Kara-Bogaz-Gol Bay (250 ‰), in the Dead Sea (over 270 ‰), water can freeze only with a very large minus - in the first case - at -6.1 °C, in the second - below -10 °C.

For the average indicator for all seas, -1.9 ° C can be taken.

Freezing stages

It is very interesting to watch how sea water freezes. It is not immediately covered with a uniform ice crust, like fresh water. When part of it turns into ice (and it is fresh), the rest of the volume becomes even more salty, and an even stronger frost is required to freeze it.

Ice types

As the sea cools, different types of ice form:

• snowstorm;
• sludge;
• needles;
• salo;
• nilas.

If the sea has not yet frozen, but is very close to it, and at that time snow falls, it does not melt when it comes into contact with the surface, but is saturated with water and forms a viscous mushy mass called snow. Freezing, this porridge turns into sludge, which is very dangerous for ships caught in a storm. Because of it, the deck is instantly covered with an ice crust.

When the thermometer reaches the mark necessary for freezing, ice needles begin to form in the sea - crystals in the form of very thin hexagonal prisms. Collecting them with a net, washing off the salt and melting them, you will find that they are insipid.

First, the needles grow horizontally, then they take a vertical position, and only their bases are visible on the surface. They resemble spots of fat in a cold soup. Therefore, ice at this stage is called lard.

When it gets even colder, the fat begins to freeze and forms an ice crust, as transparent and fragile as glass. Such ice is called nilas, or bottle. It is salty, although it is formed from unleavened needles. The fact is that during freezing, the needles capture the smallest drops of the surrounding salt water.

Only in the seas is there such a phenomenon as floating ice. It arises because the water here cools faster off the coast. The ice formed there freezes to the coastal edge, which is why it was called fast ice. As frost intensifies during calm weather, it quickly captures new territories, sometimes reaching tens of kilometers in width. But as soon as a strong wind rises, the fast ice begins to break into pieces of various sizes. These ice floes, often huge (ice fields), are carried by the wind and current throughout the sea, causing problems for ships.

Melting temperature

Sea ice does not melt at the same temperature at which sea water freezes, as one might think. It is less salty (on average 4 times), so its transformation back into liquid begins earlier than reaching this mark. If the average freezing point of sea water is -1.9 °C, then the average melting temperature of the ice formed from it is -2.3 °C.

Salt Water Freezing: Video

At what temperature does water freeze? It would seem - the simplest question that even a child can answer: the freezing point of water at normal atmospheric pressure of 760 mmHg is zero degrees Celsius.

However, water (despite its extremely wide distribution on our planet) is the most mysterious and not fully understood substance, so the answer to this question requires a detailed and reasoned discussion.

• In Russia and Europe, the temperature is measured on the Celsius scale, the highest value of which is 100 degrees.
• The American scientist Fahrenheit developed his own scale with 180 divisions.
• There is another unit of temperature measurement - kelvin, named after the English physicist Thomson, who received the title of Lord Kelvin.

States and types of water

Water on planet Earth can take three main states of aggregation: liquid, solid and gaseous, which can transform into different forms that simultaneously coexist with each other (icebergs in sea water, water vapor and ice crystals in clouds in the sky, glaciers and free-flowing rivers ).

Depending on the characteristics of the origin, purpose and composition, water can be:

• fresh;
• mineral;
• nautical;
• drinking (here we include tap water);
• rain;
• thawed;
• brackish;
• structured;
• distilled;
• deionized.

The presence of hydrogen isotopes makes water:

1. light;
2. heavy (deuterium);
3. superheavy (tritium).

We all know that water can be soft and hard: this indicator is determined by the content of magnesium and calcium cations.

Each of the types and aggregate states of water we have listed has its own freezing and melting point.

Freezing point of water

Why does water freeze? Ordinary water always contains some amount of suspended particles of mineral or organic origin. It can be the smallest particles of clay, sand or house dust.

When the ambient temperature drops to certain values, these particles take on the role of centers around which ice crystals begin to form.

Air bubbles, as well as cracks and damage on the walls of the vessel in which water is located, can also become crystallization nuclei. The rate of water crystallization is largely determined by the number of these centers: the more of them, the faster the liquid freezes.

Under normal conditions (at normal atmospheric pressure), the temperature of the phase transition of water from a liquid to a solid state is 0 degrees Celsius. It is at this temperature that water freezes on the street.

Why does hot water freeze faster than cold water?

Hot water freezes faster than cold water - this phenomenon was noticed by Erasto Mpemba, a schoolboy from Tanganyika. His experiments with mass for making ice cream showed that the rate of freezing of the heated mass is much higher than the cold one.

One of the reasons for this interesting phenomenon, called the "Mpemba paradox", is the higher heat transfer of a hot liquid, as well as the presence of a larger number of crystallization nuclei in it compared to cold water.

Are the freezing point of water and altitude related?

With a change in pressure, often associated with being at different heights, the freezing point of water begins to radically differ from the standard, characteristic of normal conditions.
Crystallization of water at a height occurs at the following temperature values:

• paradoxically, at an altitude of 1000 m, water freezes at 2 degrees Celsius;
• at an altitude of 2000 meters, this happens already at 4 degrees Celsius.

The highest freezing temperature of water in the mountains is observed at an altitude of over 5,000 thousand meters (for example, in the Fann Mountains or the Pamirs).

How does pressure affect the process of water crystallization?

Let's try to link the dynamics of changes in the freezing point of water with changes in pressure.

• At a pressure of 2 atm, water will freeze at a temperature of -2 degrees.
• At a pressure of 3 atm, the temperature of -4 degrees Celsius will begin to freeze water.

With increased pressure, the temperature of the beginning of the water crystallization process decreases, and the boiling point increases. At low pressure, a diametrically opposite picture is obtained.

That is why in conditions of high mountains and a rarefied atmosphere it is very difficult to cook even eggs, since the water in the pot boils already at 80 degrees. It is clear that at this temperature it is simply impossible to cook food.

At high pressure, the process of ice melting under the blades of the skates occurs even at very low temperatures, but it is thanks to it that the skates glide on the ice surface.

The freezing of skids of heavily loaded sleds in the stories of Jack London is explained in a similar way. Heavy sleds that put pressure on the snow cause it to melt. The resulting water facilitates their sliding. But as soon as the sleds stop and linger for a long time in one place, the displaced water, freezing, freezes the skids to the road.

Crystallization temperature of aqueous solutions

Being an excellent solvent, water easily reacts with various organic and inorganic substances, forming a mass of sometimes unexpected chemical compounds. Of course, each of them will freeze at different temperatures. Let's put this in a visual list.

• The freezing point of a mixture of alcohol and water depends on the percentage of both components in it. The more water added to the solution, the closer to zero its freezing point. If there is more alcohol in the solution, the crystallization process will begin at values ​​close to -114 degrees.

  It is important to know that water-alcohol solutions do not have a fixed freezing point. Usually they talk about the temperature of the beginning of the crystallization process and the temperature of the final transition to the solid state.

  Between the beginning of the formation of the first crystals and the complete solidification of the alcohol solution lies a temperature interval of 7 degrees. So, the freezing point of water with alcohol of 40% concentration at the initial stage is -22.5 degrees, and the final transition of the solution to the solid phase will occur at -29.5 degrees.

The freezing point of water with salt is closely related to the degree of its salinity: the more salt in the solution, the lower the position of the mercury column it will freeze.

To measure the salinity of water, a special unit is used - "ppm". So, we have found that the freezing point of water decreases with increasing salt concentration. Let's explain this with an example:

The salinity level of ocean water is 35 ppm, while the average value of its freezing is 1.9 degrees. The degree of salinity of the Black Sea waters is 18-20 ppm, so they freeze at a higher temperature in the range from -0.9 to -1.1 degrees Celsius.

• The freezing point of water with sugar (for a solution whose molality is 0.8) is -1.6 degrees.
• The freezing point of water with impurities largely depends on their amount and the nature of the impurities that make up the aqueous solution.
• The freezing point of water with glycerin depends on the concentration of the solution. A solution containing 80 ml of glycerin will freeze at -20 degrees, when the glycerol content is reduced to 60 ml, the crystallization process will begin at -34 degrees, and the beginning of freezing of a 20% solution will be minus five degrees. As you can see, there is no linear relationship in this case. To freeze a 10% solution of glycerin, a temperature of -2 degrees will suffice.
• The freezing point of water with soda (meaning caustic alkali or caustic soda) presents an even more mysterious picture: a 44% caustic solution freezes at +7 degrees Celsius, and 80% at + 130.

Freezing of fresh water

The process of ice formation in freshwater reservoirs occurs in a slightly different temperature regime.

• The freezing point of water in a lake, just like the freezing point of water in a river, is zero degrees Celsius. The freezing of the cleanest rivers and streams does not start from the surface, but from the bottom, on which there are crystallization nuclei in the form of bottom silt particles. At first, snags and aquatic plants are covered with a crust of ice. As soon as the bottom ice rises to the surface, the river instantly freezes through.
• Frozen water on Lake Baikal can sometimes cool down to negative temperatures. This happens only in shallow water; the water temperature in this case can be thousandths, and sometimes hundredths of one degree below zero.
• The temperature of the Baikal water under the very crust of the ice cover, as a rule, does not exceed +0.2 degrees. In the lower layers, it gradually rises to +3.2 at the bottom of the deepest basin.

Freezing point of distilled water

Does distilled water freeze? Recall that for water to freeze, it is necessary to have some crystallization centers in it, which can be air bubbles, suspended particles, as well as damage to the walls of the container in which it is located.

Distilled water, completely devoid of any impurities, does not have crystallization nuclei, and therefore its freezing begins at very low temperatures. The initial freezing point of distilled water is -42 degrees. Scientists managed to achieve supercooling of distilled water to -70 degrees.

Water that has been exposed to very low temperatures but has not crystallized is called "supercooled". You can place a bottle of distilled water in the freezer, get it supercooled, and then demonstrate a very effective trick - see the video:

By gently tapping on a bottle taken from the refrigerator, or by throwing a small piece of ice into it, you can show how it instantly turns into ice, which looks like elongated crystals.

Distilled water: does this purified substance freeze or not under pressure? Such a process is possible only in specially created laboratory conditions.

Freezing point of salt water

3.2. SEA ICE

All our seas, with rare exceptions, are covered with ice of various thicknesses in winter. In this regard, in one part of the sea, navigation in the cold half of the year is difficult, in the other it stops and can only be carried out with the help of icebreakers. Thus, the freezing of the seas disrupts the normal operation of the fleet and ports. Therefore, for a more qualified operation of the fleet, ports and offshore structures, certain knowledge of the physical properties of sea ice is necessary.

Sea water, unlike fresh water, does not have a specific freezing point. The temperature at which ice crystals (ice needles) begin to form depends on the salinity of the sea water S. It has been experimentally established that the freezing point of sea water can be determined (calculated) by the formula: t 3 \u003d -0.0545S. At a salinity of 24.7%, the freezing point is equal to the temperature of the highest density of sea water (-1.33°C). This circumstance (property of sea water) made it possible to divide sea water into two groups according to the degree of salinity. Water with a salinity of less than 24.7% is called brackish and, when cooled, first reaches the temperature of the highest density, and then freezes, i.e. behaves like fresh water, in which the temperature of the highest density is 4 ° C. Water with a salinity of more than 24.7 ° / 00 is called sea water.

The temperature at the highest density is below the freezing point. This leads to the occurrence of convective mixing, which delays the freezing of sea water. Freezing also slows down due to the salinization of the surface layer of water, which is observed when ice appears, since when water freezes, only part of the salts dissolved in it remains in the ice, while a significant part of them remains in the water, increasing its salinity, and therefore, and the density of the surface layer of water, thereby lowering the freezing point. On average, the salinity of sea ice is four times less than the salinity of water.

How does ice form in sea water with a salinity of 35°/00 and a freezing point of -1.91°C? After the surface layer of water has cooled to the temperature indicated above, its density will increase and the water will sink down, while warmer water from the underlying layer will rise up. Mixing will continue until the temperature of the entire mass of water in the upper active layer drops to -1.91 ° ​​C. Then, after some supercooling of the water below freezing, ice crystals (ice needles) begin to appear on the surface.

Ice needles form not only on the sea surface, but throughout the entire thickness of the mixed layer. Gradually, the ice needles freeze, forming ice spots on the surface of the sea, resembling frozen ice in appearance. salo. In color, it is not much different from water.

When snow falls on the sea surface, the process of ice formation accelerates, since the surface layer is desalinated and cooled, in addition, ready-made crystallization nuclei (snowflakes) are introduced into the water. If the water temperature is below 0 ° C, then the snow does not melt, but forms a viscous mushy mass called snowy. Lard and snowballs, under the influence of wind and waves, break into pieces of white color, called sludge. With further compaction and freezing of the initial types of ice (ice needles, lard, sludge, slush), a thin, elastic ice crust is formed on the sea surface, which easily bends on a wave and, when compressed, forms jagged layers, called nilas. Nilas has a matte surface and a thickness of up to 10 cm, divided into dark (up to 5 cm) and light (5-10 cm) nilas.

If the surface layer of the sea is heavily desalinated, then with further cooling of the water and a calm state of the sea as a result of direct freezing or from ice fat, the surface of the sea is covered with a thin shiny crust, called bottle. The bottle is transparent, like glass, breaks easily in wind or waves, its thickness is up to 5 cm.

On a light wave from ice fat, sludge or snow, as well as as a result of breaking a bottle and nilas with a large swell, a so-called pancake ice. It has a predominantly round shape from 30 cm to 3 m in diameter and up to approximately 10 cm thick, with raised edges due to the impact of ice floes one against the other.

In most cases, ice formation begins near the coast with the appearance of shores (their width is 100-200 m from the coast), which, gradually spreading into the sea, turn into fast ice. Fast ice and fast ice refer to immovable ice, i.e. to ice that forms and remains immobile along the coast, where it is attached to the coast, ice wall, to the ice barrier.

The upper surface of young ice is in most cases smooth or slightly wavy, while the lower surface, on the contrary, is very uneven and in some cases (in the absence of currents) looks like a brush of ice crystals. During winter, the thickness of young ice gradually increases, its surface is covered with snow, and the color changes from gray to white due to the brine draining from it. Young ice 10-15 cm thick is called gray, and a thickness of 15-30 cm - gray white. With a further increase in the thickness of the ice, the ice acquires a white color. Sea ice that has lasted one winter and has a thickness of 30 cm to 2 m is commonly referred to as white first year ice, which is subdivided into thin(thickness from 30 to 70 cm), average(from 70 to 120 cm) and thick(more than 120 cm).

In areas of the World Ocean, where the ice does not have time to melt during the summer and from the beginning of the next winter begins to grow again and by the end of the second winter its thickness increases and is already more than 2 m, is called two years of ice. Ice that has existed for more than two years called perennial, its thickness is more than 3 m. It has a greenish-blue color, and with a large admixture of snow and air bubbles, it has a whitish color, glassy appearance. With time, freshened and compacted by compression, multi-year ice acquires a blue color. According to their mobility, sea ice is divided into fixed ice (fast ice) and drifting ice.

Drifting ice in shape (size) is divided into pancake ice, ice fields, small broken ice(piece of sea ice less than 20 m across), grated ice(broken ice less than 2 m across), nesyak(a large hummock or a group of hummocks frozen together, up to 5 m above sea level), frosty(pieces of ice frozen into the ice field), ice porridge(accumulation of drifting ice, consisting of fragments of other forms of ice no more than 2 m in diameter). In turn, ice fields, depending on the horizontal dimensions, are divided into:

Giant ice fields, over 10 km across;

Extensive ice fields, 2 to 10 km across;

Large ice fields, 500 to 2000 m across;

Fragments of ice fields, from 100 to 500 m in diameter;

Coarsely broken ice, from 20 to 100 m in diameter.

A very important characteristic for navigation is the concentration of drifting ice. Concentration is understood as the ratio of the area of ​​the sea surface actually covered with ice to the total area of ​​the sea surface on which drifting ice is located, expressed in tenths.

In the USSR, a 10-point ice concentration scale has been adopted (1 point corresponds to 10% of the area covered with ice), in some foreign countries (Canada, USA) - 8 points.

In terms of concentration, drifting ice is characterized as follows:

1. Compressed drifting ice. Drift ice that has a concentration of 10/10 (8/8) and no water is visible.

2. Frozen solid ice. Drift ice at 10/10 (8/8) cohesion and ice floes frozen together.

3. Very cohesive ice. Drift ice with a concentration greater than 9/10 but less than 10/10 (7/8 to 8/8).

4. Closed ice. Drift ice with a concentration of 7/10 to 8/10 (6/8 to 7/8), consisting of ice floes, most of which are in contact with each other.

5. Sparse ice. Drift ice with a concentration of 4/10 to 6/10 (3/8 to 6/8), with a large number of breaks, the ice floes usually do not touch each other.

6. Rare ice. Drift ice in which the concentration is 1/10 to 3/10 (1/8 to 3/8) and an expanse of clear water dominates the ice.

7. Separate ice floes. A large area of ​​water containing sea ice with a concentration of less than 1/10 (1/8). In the absence of ice, this area should be called pure water.

Drifting ice under the influence of wind and currents are in constant motion. Any change in the wind over an area covered with drifting ice causes changes in the distribution of ice: the greater, the stronger and longer the action of the wind.

Long-term observations of the wind drift of packed ice have shown that the ice drift is directly dependent on the wind that caused it, namely: the direction of the ice drift deviates from the wind direction by approximately 30 ° to the right in the northern hemisphere, and to the left in the southern hemisphere, the drift speed is related with a wind speed wind coefficient of approximately 0.02 (r = 0.02).

In table. Figure 5 shows the calculated values ​​of the ice drift velocity depending on the wind speed.

Table 5

The drift of individual ice floes (small icebergs, their fragments and small ice fields) differs from the drift of solid ice. Its speed is greater, since the wind coefficient increases from 0.03 to 0.10.

The speed of movement of icebergs (in the North Atlantic) with fresh winds ranges from 0.1 to 0.7 knots. As for the angle of deviation of their movement from the direction of the wind, it is 30-40 °.

The practice of ice navigation has shown that independent navigation of an ordinary sea vessel is possible with a drifting ice concentration of 5-6 points. For large-tonnage ships with a weak hull and for old ships, the cohesion limit is 5 points, for medium-tonnage ships that are in good condition - 6 points. For ice-class vessels this limit can be increased up to 7 points, and for icebreaking transport vessels - up to 8-9 points. The indicated limits of drifting ice passability are derived from practice for medium-heavy ice. When sailing in heavy multi-year ice, these limits should be reduced by 1-2 points. With good visibility, navigation in ice concentrations up to 3 points is possible for ships of any class.

If it is necessary to navigate through an area of ​​the sea covered with drifting ice, it must be borne in mind that it is easier and safer to enter the ice edge against the wind. Entering the ice with a tail or side wind is dangerous, as conditions are created for the pile on the ice, which can lead to damage to the side of the vessel or its bilge part.

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If you notice, then in the sea water freezes at temperatures well below zero degrees. Why is this happening? It all depends on the concentration of salt in it. The higher it is, the lower the freezing point. On average, an increase in the salinity of water by two ppm lowers its freezing point by one tenth of a degree. So judge for yourself what the ambient temperature should be so that a thin layer of ice forms on the surface of the sea, with a salinity of 35 ppm. It should be at least two degrees below zero.

The same Sea of ​​Azov, with a salinity of 12 ppm, freezes at a temperature of minus 0.6 degrees. At the same time, the Sivash adjacent to it remains unfrozen. The thing is that the salinity of its water is 100 ppm, which means that for the formation of ice here, at least six degrees of frost is needed. In order for the surface of the White Sea, where the salinity level of the water reaches 25 ppm, to be covered with ice, the temperature must drop to minus 1.4 degrees.

The most surprising thing is that in sea water chilled to minus one degree, snow does not melt. He just continues to swim in it until he turns into a piece of ice. But getting into the chilled fresh water, he immediately conceals.

The process of freezing sea water has its own characteristics. Initially, primary ice crystals begin to form, which are incredibly similar to thin transparent needles. There is no salt in them. It is squeezed out of the crystals and remains in the water. If we collect such needles and melt them in some kind of dish, then we will get fresh water.

Porridge of ice needles, outwardly similar to a huge greasy spot, floats on the surface of the sea. Hence its original name - salo. With a further decrease in temperature, the fat freezes, forming a smooth and transparent ice crust, which is called nilas. Unlike lard, nilas contains salt. She appears in it in the process of freezing fat and capturing with needles, droplets of sea water. It's a pretty chaotic process. That is why salt in sea ice is distributed unevenly, as a rule, in the form of individual inclusions.

Scientists have found that the amount of salt in sea ice depends on the temperature of the surrounding air, which took place at the time of its formation. With a slight frost, the rate of formation of nilas is low, the needles capture little sea water, hence the salinity of the ice is low. In cold weather, the situation is exactly the opposite.

When sea ice melts, the first thing that comes out of it is salt. As a result, it gradually becomes insipid.

Young naturalists are always haunted by seemingly simple questions. At what temperature does sea water usually freeze? Everyone knows that zero degrees is not enough to turn the sea surface into a good ice rink. But at what temperature does this happen?

What is sea water made of?

How is the content of the seas different from fresh water? The difference is not so great, but still:

• Much more salt.
• Magnesium and sodium salts predominate.
• The density differs slightly, within a few percent.
• Hydrogen sulfide can form at depth.

The main component of sea water, no matter how predictable it may sound, is water. But unlike the water of rivers and lakes, it contains large amounts of sodium and magnesium chlorides.

Salinity is estimated at 3.5 ppm, but to be more clear - at 3.5 thousandths of a percent of the total composition.

And even this, not the most impressive figure, provides water not only with a specific taste, but also makes it undrinkable. There are no absolute contraindications, sea water is not a poison or a toxic substance, and nothing bad will happen from a couple of sips. It will be possible to talk about the consequences if a person is at least throughout the day. Also, the composition of sea water includes:

1. Fluorine.
2. Bromine.
3. Calcium.
4. Potassium.
5. Chlorine.
6. sulfates.
7. Gold.

True, in percentage terms, all these elements are much less than salts.

Why can't you drink sea water?

We have already briefly touched on this topic, let's look at it in a little more detail. Together with sea water, two ions enter the body - magnesium and sodium.

Sodium	Magnesium
Participates in maintaining the water-salt balance, one of the main ions along with potassium.	The main effect is on the central nervous system.
With an increase in the number Na in the blood, fluid is released from the cells.	Very slowly excreted from the body.
All biological and biochemical processes are disturbed.	An excess in the body leads to diarrhea, which aggravates dehydration.
Human kidneys are not able to cope with so much salt in the body.	Perhaps the development of nervous disorders, inadequate condition.

It cannot be said that a person does not need all these substances, but needs always fit within certain limits. After drinking a few liters of such water, you will go too far beyond their limits.

However, today the urgent need for the use of sea water may arise only among the victims of shipwrecks.

What determines the salinity of sea water?

Seeing a little higher figure 3.5 ppm , you might think that this is a constant for any sea water on our planet. But everything is not so simple, salinity depends on the region. It just so happened that the further north the region is located, the greater this value.

The south, on the contrary, boasts not so salty seas and oceans. Of course, all rules have their exceptions. Salt levels in the seas are usually slightly lower than in the oceans.

What is the geographic division in general? It is not known, researchers take it for granted, there is everything. Perhaps the answer should be sought in the earlier periods of the development of our planet. Not at the time when life was born - much earlier.

We already know that the salinity of water depends on the presence of:

1. magnesium chloride.
2. sodium chloride.
3. other salts.

Perhaps, in some parts of the earth's crust, the deposits of these substances were somewhat larger than in neighboring regions. On the other hand, no one canceled the sea currents, sooner or later the general level had to level off.

So, most likely, a small difference is associated with the climatic features of our planet. Not the most unfounded opinion, if you remember the frosts and consider what exactly water with a high salt content freezes more slowly.

Desalination of sea water.

Regarding desalination, everyone has heard at least a little, some now even remember the film "Water World". How realistic is it to put one such portable distiller in every house and forever forget about the problem of drinking water for humanity? Still fiction, not reality.

It's all about the energy expended, because for efficient operation huge capacities are needed, no less than a nuclear reactor. A desalination plant in Kazakhstan operates on this principle. The idea was also submitted in the Crimea, but the power of the Sevastopol reactor was not enough for such volumes.

Half a century ago, before numerous nuclear disasters, one could still assume that a peaceful atom would enter every home. There was even a slogan. But it is already clear that no use of nuclear micro-reactors:

• In household appliances.
• At industrial enterprises.
• In the construction of cars and aircraft.
• And yes, within the city limits.

Not expected in the next century. Science may take another leap and surprise us, but so far these are just the fantasies and hopes of careless romantics.

At what temperature can sea water freeze?

But the main question has not yet been answered. We have already learned that salt slows down the freezing of water, the sea will be covered with a crust of ice not at zero, but at sub-zero temperatures. But how far should the thermometer readings go to minus so that the residents of the coastal regions do not hear the usual sound of the surf when they leave their homes?

To determine this value, there is a special formula, complex and understandable only for specialists. It depends on the main indicator - salinity level. But since we have an average value for this indicator, can we also find the average freezing point? Oh sure.

If you do not need to calculate everything up to a hundredth, for a particular region, remember the temperature at -1.91 degrees.

It may seem that the difference is not so great, only two degrees. But during seasonal temperature fluctuations, this can play a huge role where the thermometer falls at least 0. It would be only 2 degrees cooler, the inhabitants of the same Africa or South America could see ice near the coast, but alas. However, we do not think that they are very upset by such a loss.

A few words about the oceans.

And what about the oceans, fresh water reserves, pollution levels? Let's try to find out:

1. The oceans are still standing still, nothing has happened to them. In recent decades, the water level has been rising. Perhaps this is a cyclical phenomenon, or maybe the glaciers are actually melting.
2. Fresh water is also more than enough, it's too early to panic about this. If another worldwide conflict happens, this time with the use of nuclear weapons, we can and will, like in Mad Max, pray for saving moisture.
3. The last point is very fond of conservationists. And sponsorship is not so difficult to achieve, competitors will always pay for black PR, especially when it comes to oil companies. But it is they who cause the main damage to the waters of the seas and oceans. It is not always possible to control oil production and emergency situations, and the consequences are catastrophic every time.

But the oceans have one advantage over humanity. It is constantly updated, and its real self-cleaning capabilities are very difficult to assess. Most likely, he will be able to survive human civilization and see its decline in a completely acceptable state. Well, then the water will have billions of years to clear itself of all the "gifts".

It is even difficult to imagine who needs to know at what temperature sea water freezes. A general educational fact, but to whom it is really useful in practice is a question.

Video experiment: freezing sea water