## What humidity measuring

Humidity – not temperature or time. When measuring, there are some nuances. So, before you head to the store for a desirable device, the theme is little explored. First you need to understand the basic concepts. Humidity is absolute and relative. The absolute is the density of water steam in the air. At different temperatures, this value will be different. But the relative humidity is exactly what always say in weather forecast and weather reports. In simple terms, this value indicates how much moisture not enough air until the moment when it will begin condensation. It is the device for determining the relative humidity and the need for a child's room, office or other domestic use.

## Hygrometers

Device that measures humidity is called a hygrometer. Today in stores you'll find most electronic hygrometers of various modifications. Children's room a simple and systematic control of humidity in the house, this device may be enough, especially since the price it is acceptable. However, the high accuracy of the indications of this hygrometer are no different. Sometimes they can give an accuracy within 20%.

A mechanical hygrometer will cost more than electronic, but will work more precisely. The device is a scale with an arrow. There are hair and film modifications of such a device. In the first to changes in humidity reacts long women's hair connected to the metering device. In film the role of the hygrometer sensing element plays a special thin film. Note, however, that both of the hygrometer will give quite accurate information, at low temperatures, but in the heat of their testimony can be distorted.

## Psychrometer

The most accurate device for determining the relative humidity of air at different temperatures is the psychrometer. The basis of his work is based on the difference between the temperatures on two scales thermometer – wet and dry. However, to get the result, you will have to make some effort to dampen the cloth with water, place in device and wait for some time, and then calculate the answer on a special table. However, if you are looking for really reliable data on humidity and fluctuations of 15-20% are not what you want, buy it is the psychrometer with two scales. He will not fail you.