Hydrophysicist Andrey Zatsepin: It's better not to swim in the Black Sea after rain. What happens to pool water after a rainstorm
Last week was "noted" by quite powerful showers on everything Black Sea coast. At the end of the week, the rains were especially strong in the Crimea.
Vacationers and locals anxiously awaiting the end of the storm. And as soon as the rains stopped, many immediately went to swim. But alas, it is not desirable to do this, but not everyone knows about it.
According to local authorities and experts, "the sea does not have time to clean itself after heavy rains." When bathing, water enters the mouth, and, willy-nilly, many swallow it.
An outbreak of acute intestinal infections was noted in Yalta. 61 cases of infection were recorded there, and most of the cases were children. And these are not only local residents and tourists. Poisoning was also recorded among children's camps.
The city authorities strongly recommend that all vacationers do not rush to swim in the sea immediately after showers and storms. You need to wait a bit for the sea to calm down, and therefore, "clear". And if you experience symptoms of intestinal infectious diseases (abdominal pain, nausea, dizziness, etc.), do not hesitate, and consult a doctor.
After a downpour or even light rain, it seems to you that the water in the pond has warmed up. The thing is that when it rains, the temperature environment drops quite sharply. As is known from the course of physics, in gaseous substances the distance between atoms is slightly greater than the radii of these atoms. Unlike gas, water has the distance between atoms and their radii, approximately. From a physical point of view, we can conclude from this: changing the temperature of the air is much easier and faster than changing the temperature of the water. It follows from this that when it is raining outside, the water in the sea or in the river cools noticeably more slowly. It will take days for the water temperature to drop.
You can also note the fact that salty sea water exceeds the density of the river. This is that the water in the sea cools even more slowly than in rivers.
It turns out that from the point of view of physics, water does not become warmer, but retains its temperature. So why then does a person feel that the water in the sea has become warmer?
Explanation in terms of human physiology
Once it proves that the temperature of the water does not change, the whole thing is in the person himself, namely, in the difference in the temperature of the human body and water. When the sun is shining outside, the weather is warm and calm, the human body heats up quite quickly.
The difference between the temperature of the water and the body is noticeable. Therefore, it seems to a person that the water is cold.
When it rains, it usually gets colder outside, and the sun hides behind the clouds. The temperature of the human body is getting closer to the temperature of the water, and therefore, when entering the sea, people feel that the water has become a little warmer. But in fact, the water has retained its temperature, and the temperature human body became lower.
A similar situation is with swimming in the hole, especially after the bath. When a person goes out steamed in the cold, he feels cold. Water retains its liquidity at zero or positive temperature. That is why, jumping into the hole, people do not feel the terrible cold, because it is even colder outside.
Now it is easy to sum up all of the above. After rain, the water in the sea does not get warmer. It does not change its temperature at all, and a person only feels the difference in the temperature of his body and the temperature of the water in the sea. How colder body, the warmer the water in any body of water seems to be.
The fact that in the summer after rain the water in lakes, rivers and seas becomes warmer is noticed by many people. What could be the reasons for this strange phenomenon? After all, there are absolutely no prerequisites for the sudden heating of such a large mass of liquid. Let's see what's the matter here.
Explanation in terms of physics
From the course of physics high school most people are well aware of the difference in the structure of gases and liquids:
- the distance between air atoms is much greater than their diameter;
- in water, these values are approximately equal.
This explains why air, like all gases, is much more mobile than any liquid in terms of temperature changes. That is, they heat up and cool down faster. Thus, it began to rain, the wind picked up and, of course, it became cool outside. What then happens to the water? Such a large mass of liquid, like a huge battery, continues to retain heat. Water in medium-sized lakes will need at least a day to cool down. The distance between atoms in mineralized liquids is even smaller. Therefore, sea water will lose heat even more slowly.
All this means only one thing. From the point of view of the laws of physics, water in reservoirs in the summer during rain does not heat up at all. While the air temperature drops, the water temperature stays the same. So why do people feel that the water gets a little warmer when it rains? Let's deal with this in more detail.
Physiology explanation
Since physics absolutely proves that the temperature of water in reservoirs does not change during rain, the point is in the person himself, that is, in his tactile sensations. Physiological causes they are:
- The human body heats up quite quickly on a sunny day. Therefore, the water in the lake seems to us very cold. Even in the hottest weather, few people dare to run into the river from a running start;
- When the air temperature drops during rain, the temperature of the human body also begins to drop. That is, a little closer to the temperature cool water. Therefore, we think that she warmed up. In fact, the skin that had been warmed up by the sun just cooled down.
By the way, for the same reason, people who plunge into the hole in the winter after the bath do not feel the cold. Leaving the steam room in the cold, a person begins to feel cold. Outside, the temperature is below zero, while the temperature of the water in the reservoir under the ice, and, consequently, in the hole, is above zero. Therefore, plunging into it, a person does not feel this extreme cold like outside, where it's even colder.
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Rainwater is known to have acidic properties that can negatively affect the balance of pool water chemistry. It can affect things from pH to alkalinity levels and more. Since the acidity of rain is due to industrial gases (such as NOx, SOx), you can say that you get the bases for nitric and sulfuric acid right into your pool. In addition, if the pool is buried, abundant water flows will naturally bring various materials that they come into contact with directly on the ground, bypass paths, etc. Such water entering the pool may, among other things, change calcium hardness, TDS and other chemical levels, as well as bring contaminants (eg debris, dirt) into the pool. This can affect not only the immediate water treatment, but also cause some damage to the finish of the pool due to the fact that the water in it can become corrosive. Too much a large number of outside water among other things, it affects the concentration of substances added for water treatment, significantly “diluting” or washing them out. There are many options for impact. Naturally, it cannot be said that any bad weather immediately entails problems. The degree of "complexity of the case" mainly depends on how bad the storm was. A little rain will have minimal (or no) impact, but if you want to make sure your pool water is still balanced, it's best to play it safe.
What can be done preventively if bad weather rages?
Never drain your pool before a rain storm. The weight of the water will help hold up the pool if the ground around it becomes too wet and eroded, which can cause the above-ground pool to “sag” and the in-ground pool to seem to rise out of the ground. If you are afraid that the pool will overflow, lower the water level by 20-30 cm and close the skimmer valves to prevent damage to the pump.
It is best to remove various accessories from the pool - especially those that can be carried away by the wind ( various toys, sun loungers and others) - and move them to the storage area.
It is advisable to turn off the power to the equipment - motor, filter, heater, lights - to avoid dangerous electrical malfunctions due to flooding. Protect pool equipment - even with the power turned off, it is vulnerable, can be damaged from strong winds and heavy masses of rainwater. It is better to dismantle the pump, store it in indoors or cover with a tarp and "tie" tightly to prevent water from getting inside.
Add an algicide so you can minimize the risk of natural organic pollutants from the atmosphere and make it easier to clean up after a thunderstorm.
good option, which can also facilitate the follow-up similar procedures may be the use of special protective coatings. However, here again it all depends on how strong the wind and downpour are and what type of coverage you have. If this light sunny coating, it can be torn off without problems, it can tear under the excessive weight of water and “sink” into the pool. Safe covers are much more durable and strong - plus they are usually made of a material that resists sharp gusts of wind more easily. But some owners still prefer to leave their pool open during thunderstorms that are too strong, for fear that fallen tree branches or other debris will destroy the cover. They are certainly right, but there is a caveat: these same branches and debris can cause significant damage to the finish of the pool itself, and such a replacement will be much more difficult than changing the cover. In any case, it is up to you to decide what kind of investment or justifiable risk you are willing to accept.
What to do directly during a thunderstorm?
The first step after a bad weather will be cleaning the territory. A lot of leaves and dirt will surely bring into the pool water. Be sure to clean and vacuum the pool. It is also important to check the skimmer baskets and the pump inlet filter. If they are clogged with dirt, it is important to remove it before you start the equipment again. Only after that it is worth checking the levels of chemistry.
First of all - alkalinity and pH. Since the effect on pH may not seem significant, the alkalinity will definitely be much stronger at this time. Its radical change will tell you about possible problems. Check levels disinfectant such as chlorine. Excessive water could dilute it, and besides, the “struggle” with large quantity ingesting excess contaminants can change it.
Don't worry too much about calcium or CYA (cyanuric acid) - they are usually only slightly affected by rain (unless some "thinning" is noticeable. This is not to say that shock treatment of the pool is necessary. Although it is not a bad idea either. It is definitely will remove any contaminants that may have entered the pool.
It is also a good idea to drain the excess water - this way you will return the level of the mirror to the proper level for better job skimmers. If you have diatomaceous (D.E). or a sand filter with a multi-way valve, you can simply switch it from vacuum to bleed so that excess water can escape without passing through the filter element. If the rain is constant problem, owners of pools with cartridge filters should consider installing an outlet valve downstream of the pump to pump water down to the proper skimmer level. Do not drain below the skimmer to avoid running the pump dry, which can cause other problems.
Equipment should be checked for damage and dampness. If it is in order, you can reconnect (or start) the systems. Otherwise, you should contact specialists for verification and do not perform any tests with the mains yourself. Circulation and filtration systems must be running for at least 10 hours after shock treatment of the water, so that you can definitely make sure that the water is properly sanitized. You should also turn on the heater - most likely, the water temperature has changed significantly after it was diluted by thunderstorms.
These simple and familiar procedures will allow you to cope with any bad weather without loss, so that, as in the famous song to match our anniversary issue, even on a “bad day”, your mood does not deteriorate.
If not everyone, then many people like to swim at night in the sea. I strongly do not advise you to do this while in Thailand.
Of course, there are many places in the world where marine life is much more dangerous, take the same Egypt, the coast of Australia or Florida.
But in Thailand, swimming at night or in the rain can lead to a lot of trouble.
What, you will learn by reading this article.
Why you can’t swim at night and in the rain in Thailand - Pattaya
On almost every beach there are signs with inscriptions that it is forbidden to swim at night in Thailand.
Why? Everything is very simple.
At night, if something happens to you - the current, brought your leg together, a collision with the inhabitants of the sea, there will be no one to help.
Lifeguards are not on duty on the beaches of Pattaya at night.
night for marine life very comfortable time. A lot of jellyfish, fish swim up to the shore and meeting them can be dangerous.
The same thing happens in the rain. Rain is almost always a storm, and during a storm everything is washed ashore.
At night, you can’t see anything in the sea, that is, you won’t be able to protect yourself in any way, and the risk of stepping on a hedgehog or stingray increases significantly.
Of course, you can tell as much as you like why you can’t swim at night in Thailand, it is unlikely that there will be fewer people who want to.
Since swimming at night has its own charm and romance.
If we talk about me, then I don’t swim in Thailand at night, but in the Crimea easily. But Thailand is not Crimea.
How to make swimming in Thailand comfortable and safe?
To get drunk in the afternoon and in clear water. If you are bathing children, wear a rash guard on them, it can protect them from jellyfish stings or fish bites.
Look under your feet, choose open sandy areas, avoid stones, hedgehogs and other marine life hide behind them.
It is also useful to wear swimming slippers, at least for children. sea urchins in Thailand everywhere, on Ko-Lan I saw them many times.
Do not allow children to touch the shells of the cone clam with their hands - the consequences can be the saddest if it is alive inside the shell.
What dangerous jellyfish are found in Thailand?
Almost all. And the Portuguese boat, and box jellyfish, and other species. Another thing is that it is unlikely to meet them, since although they exist,
but in a small amount and mostly offshore on islands like Koh Phangan and Phi Phi.
But, if suddenly you are stung by a jellyfish, immediately go to the hospital.
To understand whether it is poisonous or not, there may not be time.
What else is insidious jellyfish? They can hit a large area of the body with tentacles, literally slashing like whips.
The tentacles should be removed as soon as possible (not by hand) to reduce the area of penetration of the poison.
You can pour lime juice on the bite. Lime juice also dissolves the needles of sea urchins.
If we talk about Pattaya, then it is quite safe to swim here.
There are no jellyfish during the high tourist season. By at least near the coast, during the day.
On Koh Lan the water is clear and coastline small - you can see everyone and everything.
Same thing on the military beach.
Be careful during storms and cloudy weather.
It is enough just to be careful and look under your feet and around.
And at night, after all, swimming in Pattaya and in Thailand in general is not worth it.
High-profile cases when trouble happened to night bathers are not so frequent, but they do exist.
People are admitted to hospitals critical condition from the bite of a jellyfish, a stingray, species of fish dangerous to humans.
And of course, in addition to the inhabitants of the sea, at night on the beach you can simply stumble upon a company of drunk and unfriendly people,
why do you need it?
If you really want to swim at night, then let it be a pool and then, before closing it for cleaning with chemicals.
Although we are talking mainly about the Gulf of Thailand in Pattaya, the information is applicable to other regions of Thailand.
You should not be afraid of a holiday with young children at sea, the most important thing here is to conveniently plan the holiday itself, minimize financial losses and physical
costs, and also have good tour insurance for yourself and the child. Everything else will go like clockwork, because if you know in advance where you will live, on what
the beach to walk, what is there and that in which case you will be sent to a good hospital for free - there is absolutely nothing to worry about.
Insurance abroad with a child is needed is 100%. In some countries, it is needed at the stage of submission of documents, in others it is optional. But mothers with children should have medical insurance in any case, since it costs a penny, but always pays for itself. Children on vacation may often need medical help - otitis media, allergies,
ors-temperature, flu, diarrhea, poisoning and much more.
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You need insurance abroad. Any treatment is very expensive and the only way do not pay out of pocket, choose an insurance policy in advance. For many years we have been making out on the site that give the best prices It takes only a couple of minutes for insurance and selection along with registration.
It is much more pleasant to blame all these troubles on the insurance, which will quickly send you to a good hospital.
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We buy insurance online, there are the best prices and a large selection. If you do not know how to choose which insurance is best for your child and family,
