Measurements of humidity are necessary both for physics, and the weather forecaster. And this question has to interest ourselves too, especially if we long sit in one room. The humidity of air influences a human body therefore it and needs to be controlled. There are two main types of the devices measuring humidity of air. They differ in the device and the principle of work. These are hygrometers and psychrometers.
Instruction
1. The principle of work of hygrometers consists in the analysis of impact of fluctuations of humidity on certain bodies and matters. For example, hair hygrometers are based on ability of the fat-free human hair to change the length in response to changes of humidity of air. Such hygrometers measure humidity of air within 30-100%. In film hygrometers an element, sensitive to moisture, is the organic film.
2. Though film, and hair hygrometers are not capable to give such accuracy of measurements which the psychrometer gives. But in the winter fixed assets of measurement of relative air humidity are nevertheless hygrometers which are also weight, electrolytic, condensation and ceramic. Each of these types of hygrometers has the features. But base one for all: hygrometric method of measurement or definition of a dew point.
3. The Psikhrometrichesky way of measurement of relative air humidity is very popular too. At hygrometers the error can reach 5%, and here psychrometers much more precisely. The standard simplest psychrometer consists of two thermometers. One dry, and the second – damp. The second turns back in the cotton fabric moistened with water. The evaporating water cools the thermometer, and at this time the second (dry) thermometer fixes ambient temperature. Indications as a result are transferred to the registering device which determines relative air humidity indoors on the basis of a difference of temperatures of dry and damp thermometers.
4. If you have neither psychrometer, nor a hygrometer, the humidity of air can be measured also without them. Gather in a pile of cold tap water and put it in the fridge on two-three of hours. Make sure that water temperature did not fall below a mark to 5 wasps. Put a pile in the room so that it was far from heating devices. Now observe a pile within several minutes.
5. If walls of a pile began to mist over and dried in five minutes, so humidity of air very low, that is air dry; "Will report" you pile walls About average humidity, and remained misted; If on the surface of glass within five minutes small streamlets of water, so humidity of air indoors high are formed.