The question of moisture determination of air has to concern not only physicists or weather forecasters, but also ordinary people, especially in case the person carries out the most part of day indoors. Too high humidity has negative effect on health. For this reason the humidity needs to be measured and controlled constantly.
1. GigrometrPrintsip of operation of this device consists in definition of extent of influence of humidity on special matter. For example, the hair hygrometer uses feature of hair – to change length under the influence of humidity. Also there is one more kind of hygrometer which uses organic film. However it is worth remembering that these devices are less exact in comparison with psychrometers. But in winter season the hygrometer is the main device by means of which it is possible to obtain exact data on air humidity. Besides, there are some more types of such devices: condensation, ceramic, weight, electrolytic.
2. The psychrometer Using this device, you receive the most exact result (hygrometer deviation – about 5%). The psychrometer consists of two parts – the dry and damp thermal sensor. The humidity of one of sensors is reached because it is in wet cotton fabric. Eventually moisture evaporates and by that cools the thermometer. Along with it other sensor takes exact indoor temperature. As a result the obtained data are transferred to the special microprocessor which defines exact air humidity.
3. However happens that there are no such devices near at hand simply. In that case you can receive only approximate value of humidity by means of the following method. Having poured cold water into small glass, put it in the fridge for 2-3 hours (water has to be cooled up to 3-5 degrees). Then put glass to that room in which it is necessary to measure humidity (you remember that it has to be as it is possible further from heating appliances). Further within 5 minutes watch the surface of glass carefully: - if on walls of glass streamlets were formed, then it speaks about high humidity indoors; - if the surface remained misted over, then indoors normal humidity; - if walls in 5 minutes have dried, then it means that indoor air too dry.