Those who have any long lived in the villages, they know that even the grass on a summer morning is almost always wet with dew.But probably few people wondered why this is so.Where does this water, and what is the general nature of this phenomenon?
What is the dew point?
The weather forecasts are usually it is only the air temperature, precipitation, wind and atmospheric pressure.Meanwhile, there are still many important characteristics that give an idea of the environmental conditions.Among them, the dew point.This term is familiar to many people, but not everyone knows what it is, and what does this figure.So what is the dew point?
By this phrase is meant a measure of air temperature, at which the saturation limit of its moisture, resulting in water begins to condense either in the form of water droplets on the surface or in the form of mist.Sometimes it does not matter, and in some places this information must be considered.
water vapor contained in the air is always in one way or another.And the dew point - a combination of certain factors, for which there is a transition from the gaseous to the liquid state of aggregation.When the condensate formed on the subjects with the lowest temperature, so as to cover the pan of boiling water.Sometimes it brings problems such as tenants poorly insulated homes or owners of improperly installed glazing may be faced with constant dampness and misting.
Mechanism of
So, what happens when the night or early morning, the air temperature drops?That is what the dew point of view of physics, and what processes take place when it is reached?Very interesting.
Near the surface of the coldest objects formed a thin layer of gas at the same temperature.Its thickness may be meager, but it is there condensation falling on the surface of the object.The street is primarily can be stones, metal structures, grass.This occurs if the temperature is above the dew point.In winter, everything is a little bit different.This phenomenon can be observed while breathing in the cold when the steam comes out of his mouth.Rapidly cooled, water in the gaseous state is transformed into small droplets.Something similar happens in the atmosphere at high cloud formation.
Effects
But why is this happening?First and foremost on the condensation temperature affects the environment and objects.In addition, the importance of relative and absolute humidity.The greater these indices, the above dew point.When absolute humidity, the figure will coincide with the actual weather conditions.
Also important is the pressure in the first place if necessary to calculate the dew point in a compressed air.Physicists continue to carry out experiments in a variety of settings.In this case distinguish species outside the indicator and also under pressure.Ceteris paribus the second figure will be much lower.
Calculation of
So now it was clear that such a dew point, and what affects it.But how to calculate at what value the temperature and humidity begins to condense water vapor?There are special tables and formulas that can be used to calculate this index with a small error.Calculating the dew point temperature of these methods considers only the relative humidity and temperature so that the gas pressure, none of these methods are not suitable.
course, still have special devices that allow to fix the rate - psychrometers.Their main purpose - to determine the humidity, but for determining the dew point, they are also perfect.
value Construction
primarily determining the dew point temperature has a value in the design of buildings.Water has a deleterious effect on the metals, due to its corrosion begins, so that the formation of excess moisture can cause premature wear of the structure.If the temperature is high enough, the process will take place at high speed.
It also has implications for people for whom the issues are extremely relevant home insulation in winter.In winter, the outside of the building is much colder than the inside.Thus, the temperature drop is unavoidable.And here it is important that the dew point in the wall was as far away from the inner surface.Otherwise, residents face the risk of eternal humidity, dampness, mold and other effects.So during the construction of housing as apartment and private homes need to consider this factor.The dew point of the wall is achieved in any case, reducing the temperature, but the problem of builders is to make it as close as possible to the outer layer.
And all the metal structures to be coated with a special anti-corrosion compounds, and to organize an effective diversion of excess moisture from them.Within the walls of homes that are not only hygroscopic materials, but also special waterproofing.The complex as it allows residents do not suffer because of the ever-wet and cold corners or window sills.
value in aviation
Aircraft flying high in the air where the temperature is lower than that of the earth.And condensation can affect the aerodynamics.This is especially important during takeoff and landing, so among other environmental indicators required to calculate the aeronautical meteorology and dew point.It helps to take into account the possible formation of clouds and fog, if the actual temperature is close to it.In winter, this information is also important, because the cold weather is necessary to think of the possible icing of the aircraft and prevent it by means of special reagents which are applied to the airframe.
value in other areas and Countermeasures
In addition, this figure also allow manufacturers of paints, lacquers, protective compounds.Naturally, manufacturers and users of precision optics should also be aware of this factor, so as not to harm the technique, especially if you have to bring equipment into a warm room from the street.
In order to avoid condensation inside the building, it is necessary to provide proper ventilation and water diversion.For example, some people who want to save money, may be faced with a permanent fogging or leaking windows.Defective or improperly installed plastic windows can be a source of constant problems.So it is better to entrust this work to professionals good.
microclimate and comfort
And what is the dew point for the people?How do they feel under conditions where condensation?Here first is the relative humidity value.At a sufficiently high temperature and saturation index of air with water vapor people think that in the street or in a room stuffy.This is particularly felt the residents of temperate climate, arriving in the summer in the tropics or subtropics.With almost one hundred percent humidity dew point is almost the same as the actual temperature of the air, and people literally become impossible to breathe, especially if it is very hot.In such circumstances, some may have problems with the cardiovascular system, you can also get heat stroke, so the sharp deterioration of state of health is necessary to the doctors.
