There are different methods of laying panel heating. One of them is a warm floor of the soil. The peculiarity is that such heating is being done during the construction of the building, and not subsequently its operation, as a result of the desire to upgrade housing.
Scheduled to make a warm floor on the ground in a private house, you should smash all the work into two stages: the black screed is poured onto the lower layers, then all the other cake layers are laid out. This iron rule for laying, dictated by a possible shrinkage of soil.
The design of the warm floor, which is placed in the premises, resembles a kind of "pie", because consists of several layers.
The fill of the warm floor on the soil directly depends on the characteristics of the soil. It must meet certain requirements and regulations.
Thus, underground waters should be no higher than 5-6 meters from the level of the upper layer. It is important that the soil of the site does not have a high value of looseness and airiness. Therefore, construction works on sandstones and chernozem are not allowed. It is also important to consider the load that will be on the design during operation. The floor must ensure the following:
- reliable thermal insulation of the room;
- do not give groundwater to flood the room;
- eliminate external noises;
- prevent water vapor penetration;
- ensure comfort residents.
Water warm floor of the soil
The design of the panel heating is an excellent solution for residential rooms and work rooms with a large area (more than 20 m2). Here you can use electrical heating or water. In small rooms (bathroom, balcony or loggia) is quite difficult to postpone. Therefore, it is allowed (and even recommended) the use of electric warm floors. As a rule, everyone is striving to provide comfort primarily in large rooms. It is worth considering the water floor of the soil, its features.
It's important to know! Laying the water panel heating system is prohibited in high-rise buildings together with a centralized heat source. This is due to the depressurization of the system, making additional resistance to a calculated pre-project, which will prevent the correct work.
Based on this, it is worth understanding that to connect heating it is worth considering the availability of an autonomous heat source. And for this you need to contact the relevant government structures for the resolution.
There are several methods of installation of water systems. But for each of them you need to provide the following:
- When laying on the ground it is necessary to take care of the organization of a kind of "pillow". The first layer of sand is stacked (thickness 5-7 cm), then the stone is a fine fraction (the thickness of the layer is 8-10 cm).
- The second stage is waterproofing. You can use almost all available materials. Fits bitumen rubber or bitumen-polymer mastic. Alternatively, you can use the inlet type. This option has reinforcement in the form of fiberglass.
- Do not do without thermal insulation. Can be used polystyrene foam. The thickness of this layer is variable and depends on the calculations carried out.
- You can use the additional layer of heat insulation of the coated foil coating (this is an auxiliary design, because this step can be skipped).
- Laying pipes of a warm floor on the soil.
- On top of the pipeline there is a screed. It will be required and its reinforcement by the grid. The height of such a design together with heating elements should be 50-70 mm. This is done to quickly warm the coverage. Reinforcement is carried out above the design of the warm floor. This is done with the aim of uniform distribution of loads on the system.
- Finish coating. It is allowed to apply materials that are not amenable to thermal exposure to the outdoor heating system.
Basic errors when installing a warm floor on the ground
How is the floor screed on the soil for a warm floor
The current methods of installing a concrete screed on the ground are divided, as a rule, at 4 main stages:
- preparatory work;
- pouring a concrete screed;
- plane processing;
- sealing cake.
Of particular importance is the layered cake structure. It includes the following:
- the basis (it must be seal before performing subsequent work);
- fine sand;
- crushed stone;
- layer of waterproofing;
- primary concrete coating;
- protection against steam;
- panel or rolled insulation;
- pure concrete screed with reinforcement.
Preparatory work begins with levels. This will determine the level of soil and sex of the future building. The soil must be compacted by applying special units.
The waterproofing layer can be performed from membrane materials. It is put forward by the only requirement - integrity. Otherwise, damage can be fraught with floodings. The maximum tightness of the layer will achieve its laying of the brass with the fastening of parts by assembly scotch.
A black screed is made of skinny concrete with an admixture of rubble shallow fraction. Special requirements are not put forward to such a surface. By the way, it can have drops at an altitude of up to 4 mm.
The insulation of floors on the soil involves the use of quality materials. Ideally, this layer must perform the function of not only thermal insulation, but also to protect the room from the penetration of water. This will make it to a greater degree to secure the house from the flood.
Installation of the finishing screed is held in several steps.
Important! Reinforcement directly depends on the calculated loads on the warm floor.
With a slight value, you can use the road grid. If the expected loads are quite large, it is recommended to use a frame from iron rods with a diameter of 8 mm.
At the end of the work, the installation of guides of beacons and the finishing fill of the cement-concrete mixture is carried out. The final stage is the floor alignment.
Heat loss through the floor on the ground. How to calculate?
Thermal losses through the design of the floor are calculated a little different than through other enclosing structures. Before laying heating, you need to get acquainted with the methodology for their definition.
The entire plane is divided into the zones of a certain size. All of them 4:
- The horizontal component of the Zone I is 2 m from the wall. The vertical component is the thickness of the bearing wall, which will be needed to be insulated. It is 1.5 m.
- Zone II is another 2 meter of the floor. The area begins directly from Zone I to the center of the room for which the calculation is carried out.
- Zone III - the next 2 meters. This area originates from the II zone.
- And zone IV - the remaining floor area of \u200b\u200bthe room.
After the sketch is drawn. If the room is small, the conditional separation may not be 4, but by 2-3 zones. Next is the thermal resistance for each area.
Regulatory literature states that it should be 2.1 m2 ° C / W. To ensure this indicator you need to know the thermal conductivity of each cake layer. The second area has a regulatory resistance of 4.3 m2 ° C / W. Third - 8.6, and the fourth - 14.2.
After determining the thermal resistances, for each zone, it is necessary to immediately calculate the area. In addition, the difference between the temperatures of the outer and internal air should be known. For the calculated value it is worth taking the temperature of the coldest five days.
After that, heat loss is calculated, guided by the formula:
- Q \u003d S * T / R, where:
- Q - Warm loss, W
- S - the calculated area of \u200b\u200beach zone, m2
- R - thermal resistance of the enclosing structure, m2 ° C / W
- T - temperature difference.
When the calculation of the heat loss for each floor zone is complete, it is necessary to calculate the total value for the entire room. To do this, you need to complete the results obtained for each site.
Cake of warm floor on the ground: laying features
Earth grounds on which heating will be mounted, should be prepared. For this purpose, the soil is aligned, the seal of the upper layer is carried out. If it is necessary, the ground layer falls on the ground. It consists of rubble or gravel. Most often used medium fraction. This prevents the capillary penetration of groundwater into the room. The need to lay such a "pillow" occurs only in the case of a high level of groundwater.
A bed with a black screed, which was mentioned above, also has certain nuances. Thickness should be from 50 to 100 mm. The concrete brand used is M100 or M200. It is advisable to carry out the reinforcement of the sole in the case when the soil was poorly sealed. Also, its use is justified in the case when there is discrepancies in the density of the base.
Council. If there are pits or trenches, reinforcement is a necessary piece of cake.
A rough screed for a warm floor on the ground in a private house can be laid on the overlap of basement. This is done in order to level the plane. The thickness of such a layer should not be less than 3 cm.
There is also a phenomenon like a dry screed. Its use has gained popularity due to the fact that there are no wet concrete works. Use the technology is advisable only for the arrangement of a draft screed.
When laying a warm sex on the ground, you should take care of the deformation layer. Dampfer tape will help here. The material will negate the likelihood of a thermal bridge. It also compensates for the load that occurs when the concrete coating is heated. It does not give the screed expand and crack. The damper tape is placed on all sides of external enclosing structures. But this is done solely after applying plaster and preparatory work on the finishing of the building.
Concrete floor of the soil in a private house is a long-known universal way to arrange a reliable and warm base. Due to the use of new types of insulation, we obtain good thermal insulation of the entire floor, which leads to a decrease in utility costs. As well as the insulation is an obstacle to penetrate moisture and the appearance of fungus and mold.
And the most important thing is that this type of gender you can build your own hands. In this article we will analyze all the advantages and disadvantages. Consider the floor arrangement in detail on the soil.
Paul by soil: pros and cons
Let's start with the fact that this type of floor is a "puff pastry". And each layer has its own functions and its purpose, due to such a device, the floor on the soil has several advantages:
There are not many shortcomings, but they are all, they are:
Cannot be used on wicked soils.
How to make the right floor design on the soil
We will consider the right classic floor structure with you, which will consist of 9 layers. Each layer will understand separately.
Immediately it is worth saying that every wizard and specialist the number of layers can change, and the materials may also differ.
This type of floors is ideal for the ribbon type of foundation. The average thickness of the "Floor Cake" approximately is 60-70 cm. This should be considered when the foundation is erected.
If you do not have enough foundation, we choose soil, to a given depth. Running the surface and tamper. For convenience in the corners around the perimeter, a scale should be made in increments of 5 cm. It will be more convenient to navigate in the layers and levels.
It is important that the soil is best to rent a vibroplite, since a manual way will take a lot of time and will not give such results as a special device.
Clay. If during the sample of the Earth you reached the clay layer, then you should not fall asleep a new one. The thickness of the layer must be at least 10 cm. 
Clay is sold in bags, it is pouring it out and wetted with a special solution (4 liters of water + 1 teaspoon of liquid glass), and we carry out the tamper using vibratinglitis. After tamping, shed a layer of clay cement milk (10 liters of water + 2 kg. Cement).
Make sure that there is no puddle. As soon as you spend this composition of clay, the process of crystallization of glass begins.
The day should not be done, it is worth waiting for the crystallization process to grab, and it will end in approximately 14-16 days. This layer prevents the main flow of water from the soil.
Layer of waterproofing material. The task of this layer, protect the insulation from moisture. You can use runneroid, polymer-bitumen materials, PVC membranes and polyethylene film with a thickness of at least 0.4 mm.
In the case of the runner, it is preferable to put it in two layers, on liquid bitumen. Put the waterproofing of the mustache between themselves and on the walls.
Between themselves 10-15 cm, and on the walls on the height of the floor level. Suts are definitely sick by the construction scotch. Waterproofing material should be walking in soft shoes.
Insulation + layer of vaporizolation. The best insulation material is extruded polystyrene foam (EPPS). For an EPPS certificate, a thickness of 5 cm. Can replace 70 cm. Layer of clay.
But so, you can use pelitobetone and opilk concrete. The insulation sheets are laid without junctions, so that one plane formed.
Thickness is determined depending on the region, the recommended thickness of the insulation is 5-10 cm. Some are used with mats with a thickness of 5 cm.
In order to remove the bridges of cold from the foundation or base, the insulation is placed vertically and fasten with a dowel from the inside. Experts recommend to insulate the base and outside, with one sheet of insulation and also fasten with dowels. 
From above the insulation, it follows, lay a layer of vaporizolation. PVC membranes are best used as a vapor insulation material, they are not amenable to the process of rotting and have a long service life. The minus of this material is the high cost.
The main task of a vapor barrier material is the protection of the insulation from the descending alkaline effect of the concrete solution. The material is placed on the bracket 10-15 cm. And sample the construction scotch.
Smoothing We produce using the rule or vibration. As soon as the solution serves, the beacons should be removed, and the cavities are filled with mortar.
All concrete floor should be covered with a film and water periodically. A month later, concrete will take full force. To pour concrete with your own hands, make a solution of the following composition: cement + river sand in a ratio of 1 to 3.
In the case of the use of warm floor, water or electric technology. Must be mounted using a black screed of the floor on the soil. 
After laying the insulation, a laying of pipes or wires. Then poured the cavities with concrete, we put the reinforcing elements and continue to fill the concrete to a specified level.
Floor floors can be used not only in brick and stone houses, but the same, in the houses of wood. With the right approach and correct calculations, the layers do not harm the wooden elements.
Finish flooring. The resulting concrete surface is suitable for any kind of pure flooring. It all depends on your preferences and financial capabilities.
As it was above the combination of components, and the number of layers may be different. It all depends on your finances and opportunities.
Conclusion
As we all know that through the floor can leave from 20 to 30% of heat. In cases where there is no "Warm floor" system, the floors should be as thermally insulated, and this in turn increases the energy efficiency of the whole house.
The owner of a private house receives comfort, comfort and savings on payments for utilities. Floor floors with insulation are a highly efficient and long-term choice of each owner.
A warm flooring device in itself is considered a complex engineering task. If the floor is directly in contact with the soil and serves as a part of the liquid heating system, the probability of making a mistake grows at times. Today it will be a question of both the materials used and the phased device.
Laying of warm sex on the ground belongs to complex engineering events. This means that the Contractor lies not only for the effectiveness and long service life of the heating system, but also for the normal behavior of the floor covering under cyclic heating conditions. Therefore, proceed consistently and strictly follow the recommendations on the device technology.
What pipes are suitable for warm sex
The first thing to do is to determine the type of thermal tubes. While the question is solved with the acquisition of the desired type of product, you will have time to spend all the necessary preparatory work. In addition, you will be known from the very beginning of the pipe fastening system, and you prosecute everything you need for this.
So, we will start with the failure of pipes that do not have such a targeted purpose as use in warm floor systems. This will include metal-plastic polyethylene pipes connected by the press fitting system and the PPR tube for the soldering of plastic water supply. The first does not give themselves in terms of reliability, the second is poorly carried out heat and have high temperature expansion coefficients.
Initially, a convenient and reliable mounting system of temporary fastening of pipes is selected. This may be a reinforcement grid, to which the pipes will be tied with wire, but imagine installation in this way on the square from 100 m 2 or if suddenly a few ties will break off in the process of filling concrete. Therefore, you should use the mounting substrate or the system of the rail. They are attached to the base of the floor, while the pipes are not yet laid, then the tubes are fixed in the guides with clips or click-clips.
The fastening system itself can be plastic or metal. There is no particular difference in this, the only thing to pay attention to is how reliable the fixation and whether the guides themselves cannot damage the pipes.
Finally, we are determined with pipe material. There are two types of products recommended for use in warm floor systems. For both, the installation technology eliminates the influence of the human factor during bending and compound.
Copper. Despite the increased cost, the copper tubes are easy to lay in, for soldering you will need a flux vial and gas burner. Copper best manifests itself in the "fast" warm floor systems, which works in parallel with radiators, but not on an ongoing basis. The bend of copper tubes is carried out according to the template, respectively, their break is extremely unlikely.
Polyethylene. This is a more common class of pipes. Polyethylene is practically not affected, but for the installation will require a special crimp tool. Polyethylene may have different density, it is recommended not lower than 70%. It is also important for the presence of an inner oxygen barrier: polyethylene is badly resisted by the diffuse penetration of gases, at the same time water in the pipe of such a length may pass in significant oxygen volumes from the external environment.
Preparation of soil
When the warm floor is used, the "pie", the thickness and filling of which is determined individually. But these data are important already at the first stage of work so that, if necessary, deepen the earthen floor and not sacrifice the height of the room.
In general, the soil is removed by 30-35 cm below the level of the planned floor covering received for the zero point. The surface is thoroughly aligned in the horizontal plane, the layer of geotextiles is befell by incompressible material, in most cases it is used to use PGS.
After a thorough manual breakdown, the low-brand is prepared by concrete. For the purposes of additional thermal insulation, this layer may consist of a slight ceramzite concrete. It is important that the surface is removed into the overall plane located below the zero mark on the thickness of the cake plus about 10-15 mm.
Selection of insulation
Water heating cake consists of a heater, tightly squeezed between two layers of a cement-sand tie. The insulation itself is presented a fairly narrow number of requirements.
Mainly normal compression strength. Ideal extruded polystyrene foam density from 3%, as well as PIR and PUR-slabs as more fireproof. If you wish, you can use the plates of mineral wool brand 225 according to GOST 9573-96. From watts, they often refuse to maintain the complexity of its installation and the need to cover the insulation of the hydrobarier (polyamide film). It is characteristic that the minimum stove thickness is 40 mm, while when the reflective screen device from the EPPS, the thickness of the latter rarely exceeds 20-25 mm.
The polymer materials also serve as a good barrier on the way moisture migrating from the soil, the waterproofing device is not required with them. Many can stop the dubious safety of styrene-containing material or the price of more expensive plates with complete chemical inertia (PUR and PIR).
The thickness of the insulation is determined by the heat engineering calculation. If a concrete with a clamzite was used in the preparation as a filler, 10-15 mM EPPS or 60 mM mineral wool will be enough. In the absence of insulated preparation, these values \u200b\u200bneed to be increased by 50%.
Preparatory and accumulating ties
It is very important that the insulation will be tightly clamped between two screeds and any of its movements or fluctuations were excluded. Concrete floor preparation is aligned with the preparatory screed, then with the tile glue under the comb sticks the insulation plates. The glue also close all the joints. If mineral wool is used, concrete preparation must be pre-coated with a layer of penetrating waterproofing.
The screed layer over the insulation must have such a thickness so that its overall thermal conductivity is at least 3-4 times lower than that of the heat screen. In the general case, the screed thickness is about 1.5-2 cm from the total height of the ceilings, but to adjust the inertia of a warm floor with this value, you can freely "play". The main thing is to change the thickness of the insulation accordingly.
The top layer of the screed, subjected to heating, is poured after the wall fencing by damper ribbon. The pouring of the accumulating screed can be held in two stages for convenience. On the first pour about 15-20 mm with a rare mesh reinforcement. According to the obtained plane, it is convenient to move and secure the system mounting system, the residue is poured to the level of zero mark less the thickness of the floor covering.
1 - compacted soil; 2 - sand-gravel benching; 3 - preparatory reinforced screed; 4 - hydrotreating; 5 - insulation; 6 - reinforcement grid; 7 - warm floors; 8 - cement-sand screed; 9 - floor covering; 10 - damper tape
Installation of the system, proportion and step loop
Laying of warm floor pipes should be carried out according to the scheme in advance and drawn on the floor. If the room has a form other than rectangular, its plan is divided into several rectangles, each of which is represented by a separate coach of the loop.
The same principle is used in the zoning of the floor. For example, in the game area of \u200b\u200bthe tube can be laid by a more frequent step, and they are preferably not allowed under body furniture at all. In each separate twist of the rectangular shape, depending on the priority of heating, the tubes can be laid either snake or snail or combine options. The general rule is simple: the further the specific point from the beginning of the duct, the lower its temperature, there is an average of 1.5-2.5 ºС every 10 meters, respectively, the optimal loop length is in the range of 50-80 meters.
The minimum distance between adjacent tubes is determined by the manufacturer according to the allowable bend radius. A more dense gasket is possible according to the "snail" scheme or with the formation of wide loops at the edges of the snake. Optimally adhere to the distance equal to the 20-30 values \u200b\u200bof the tube diameter. It is also necessary to make a correction to the thickness of the accumulating screed and the desired heating rate of the floor.
The installation system is mounted on the gasket route through the insulation to the concrete preparation layer, respectively, the length of the fastener (usually plastic BM-dowels) should be 50% more than a distance to the surface of the preparatory screed.
When laying the pipe, you should figure out the improvised spool for unwinding, otherwise the tube will constantly twist and break. When all loops are fixed in the mounting system, their high pressure test is carried out and if the test results are satisfactory, the upper layer of the accumulating screed is poured.
Turning on the warm floor to the heating system
It is recommended to put one-piece pipe cuts in the layer of screed without connections. Helping tails can be reduced either to local manifolds or drive directly into the boiler room. The last option is usually convenient with a small removal of the heated floor from the boiler or if all rooms have a common corridor, which is sufficiently deprived.
The ends of the pipes are rolled by the expander and are connected with crimping or soldering with threaded fittings for connecting to the collector node. Each of the taps is supplied with shut-off reinforcement, ball cranes with a red flywheel are installed on the feed tubes, on the return - with blue. The threaded transition with the locking reinforcement is necessary for the emergency shutdown of the individual loop, its purge or flushing.
An example of a water warm floor connection scheme to the heating system: 1 - heating boiler; 2 - expansion tank; 3 - security group; 4 - collector; 5 - circulating pump; 6 - collector cabinet heating radiators; 7 - Color Cabinet Warm Paul
Connecting collectors to the heating line is performed by analogy with heating radiators, two-pipe and combined inclusion schemes are possible. In addition to the thermostat, the collector nodes can be supplied with recirculation systems that support the comfortable coolant temperature in the supply of about 35-40 ºС.
Floor arrangement is one of the most important points in repairs or construction. And if we are talking about a private house, this question becomes more acute. In many projects of houses, floors are very often design, it is quite reliable and one of the most practical and inexpensive options. Currently, the warm floors are becoming increasingly matched and popular every day, so many have preferences precisely this type of heating in the house. Reliable heat insulation will provide heat and comfort in it, and will also significantly reduce the cost of its content. After all, warm floors retain warmly in the house, create comfortable conditions for living, and in some cases replace central heating.
What is a cake of warm sex on the soil
Arranging the floors on the ground, the mandatory moment is their heat insulationThanks to this, it turns out a multi-layered construction, which is very often called a heap cake. This design is largely reminiscent of puff pie, as it consists of several layers. I would like to say that the construction of sex on the soil depends largely on the state of the soil. It must comply with some requirements. For example, the level of groundwater should be at a depth of 5-6 metersThe soils should not be loose, for example, sandy or black earth. In addition, it is necessary take into account the load on the floor. It should be noted that the cake of the warm floor must provide:
- thermal insulation of the room;
- protection against groundwater;
- soundproofing in the house;
- prevent from the accumulation of water vapor inside the floor;
- ensure comfortable living conditions.
What is the cake of warm sex on the soil
By its design, the cake of the warm floor on the ground consists of several layers, the laying of each layer occurs in stages.
Depending on the structural features of the floor and some other important factors, the patter of the warm floor on the soil may have a different composition and different thickness.
Advantages and disadvantages of warm sex on the soil
Dignity:
disadvantages:
- warm floor, depending on the design features, can significantly reduce the height of the room;
- in case of malfunction of this system, dismantling layers of the floor will be very difficult and expensive;
- sometimes it enough long and complex procedurewhich is advisable to perform during the construction of the house;
- need to consider the position of groundwater.
Warm Paul Cake Styling Options
There are several options for laying a heap cake along the soil. This may depend on the level of groundwater passage, the operational loads on the floor, the type of heat and some other factors. The above option can be considered the main one, where it goes as the main underlying layer Concrete layer. Piece of cake and in another way, where the concrete layer replaces the sand pillow, its thickness is 100-150 mm. The sequence is the same, although it is much more complicated to provide an even base than with a concrete screed.
Depending on the thermal insulation materials, there may also be various options for the heap cake. Choosing as insulation polystyrene foam, Pie styling will be as follows:
Excellent insulation - mineral wool plateswhich have high density, resistant to deformation and durable. This material is advised to lay in two layers. For less absorption, moisture is treated with water-repellent composition. Used as a heated layer in a warm floor cake and clay. This is a fairly simple and inexpensive option. When laying cake applying ceramzitAs a heater, you can not lay additional waterproofing, also replaces the gravel layer and screed. There are some more pretty effective ways to lay heat cake using some other thermal insulation materials.
Warm Paul Cake Mounting Technology
Available floors on the ground - this is one of the most successful options that reduces the cost of their construction, saves time and labor costs. A competently equipped with a warm floor cake will provide heat, comfort and comfort in the house for many years.
In his house, you may need a device of water warm flooring on the soil. Designed to comply with existing SNiP, you can independently perform work, ranging from the intake and ending with a finishing screed, followed by flooring.
Is it possible to do water field to soil
Piece of water heating floor on the soil can be performed subject to the use of the method of mounting the heating system using a concrete screed. Styling allows you to simultaneously achieve several goals: make a draft floor and prepare a base for the finish coating.The design of water-free floors in the soil provides for carrying out works that are commonly used to prepare concrete slabs in industrial and residential buildings. The result of the work largely depends on the achievement of several tasks:
- Ensuring reliable heat insulation that prevents floor freezing.
- Protection of the room from the appearance of dampness.
- Preventing the slab cracking after several years of operation.
What a "cake" should be under a warm floor
The diagram of the floor of the floor on the ground is somewhat different from the usual pie used for the installation of the heating system by the already finished base. The following stages of work are performed:
To make the water floor of the soil with your own hands, you will need from 20 days to 1.5 months. You can speed up the installation process by ordering ready-made cement mixtures.
Main errors when installing water floors
Performing work on a bulk soil, it is easy to allow mistakes leading to the destruction of the slab in the future. It is required to strictly observe the phased production of the water heating cake, starting with the soil. It would be optimal to pre-perform a heat engineering calculation, which makes it possible to accurately determine the thickness of the powder, thermal insulation and the power of the heating system.
Common errors during installation are:
- Violations of warm water floor installation technologies for soil. The absence of compensation gaps in the stove, poorly performed works on the rashpin, incorrectly laid waterproofing, subsequently become the reason for the fruit of the screed, the accumulation of condensate and dampness indoors.
- On the ground base, be sure to wake up sand in front of the rubble. At the same time, you can use any kind of raw materials, but the optimal will be the river sand of a large fraction. The minimum density of the soil after tamping depends on the weather and atmospheric conditions of the area and is calculated on special tables.