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Useful information about thermometers, hygrometers and barometers
Thermometers, hygrometers and barometers are used to determine temperature, air humidity and air pressure. They are one of the most important measuring instruments for weather observation and are used in many other areas. You can find out what was specifically distinguished by the measuring instruments and what was important when purchasing them in our guide.
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What was thermometer, hygrometer and barometer?
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Analogueue and digital thermometer, hygrometer and barometer
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Thermometer, hygrometer and barometer in weather stations
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Buying criteria for thermometers, hygrometers and barometers – what's it all about?
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Our practical tip: Attach thermo-hygrometer correctly
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FAQ – Frequently asked questions about thermometers, hygrometers and barometers
Was thermometer, hygrometer
Barometers
Thermometers, hygrometers and barometers are used for different measuring tasks. While thermometers are used to measure the temperature of liquids, gases or bodies, hygrometers are used to determine relative humidity in the air. Barometers, on the other hand, measure the air pressure. The application areas of thermometers, hygrometers and barometers are varied. They are used in industry, crafts and science, but also in private households. Hygrometers are used, for example, in construction for the regular measurement of the air humidity, because moist air in the room is directly related to mold formation. Barometers are used in air and sea transport as well as in mining. The application area of thermometers is probably the largest. From bath thermometer to fever thermometer, there are a whole range of different types of thermometers that are suitable for different applications.
Analogueue and digital thermometer, hygrometer and barometer
Thermometers, hygrometers and barometers are offered in analogueue and digital versions and differ in their function accordingly. The digital models all work the same in some ways: They have sensors and an electronic unit that receives the data. The type of sensor used varies depending on the measuring instrument and the application.
Thermometers, barometers and hygrometers function differently in analogueue form. Analogueue thermometers measure the temperature, for example, by the thermal expansion of liquids or bimetal strips. An example of analogue barometers are dose barometers. As the name suggests, they consist of a nearly empty can (usually made of metal) and a pointer that is linked to a tensioned spring. As the air pressure increases, the can is compressed, was pressure applied to the spring. This causes the measuring pointer to move.
Analogueue hygrometers measure humidity in the air, among other things, by means of hair. Such designs are also known as hair hygrometer. They take advantage of the fact that hair expands or contract depending on the degree of humidity. The more moisture in the air, the longer the hair is. The change is transmitted via a lever system to a pointer indicating the corresponding value on a clock face.
Thermometers, hygrometers and barometers are also available as combination measuring devices. One example of this is the thermo-hygrometer (thermometer hygrometer), which measures the temperature and humidity of the air at the same time. They are useful for controlling the indoor climate and are used in libraries and museums, but also in horticulture and transport. Thermo-Hygrometers are also available as analogueue and digital versions as well as individual measuring instruments. If you are interested in an electronic thermo-hygrometer, but do not want to lay any cables for data transmission between outdoor sensors and receiver, you can decide for a wireless thermo-hygrometer, which sends the measured values via radio signal to the receiving station.
Thermometer, hygrometer and barometer in weather stations
Thermometers, barometers and hygrometers are an important part of weather stations. They provide measurement results with which statements about the current weather as well as weather forecasts can be made. Temperature, air humidity and air pressure are related to each other and determine the climate. For example, a high humidity and a high air temperature provide for humidity. Weather forecasts are based on air humidity and air pressure data. If the relative humidity and the air pressure change, the weather is about to change. As a rough rule of thumb, the weather improves when the air pressure increases and worsens when the air pressure decreases.
In principle, a weather station is nothing more than a combination of different measuring instruments. In addition to thermometers, barometers and hygrometers, this also includes rain and wind gauges, which are usually installed as outdoor sensors. Weather stations for domestic use are far from as extensive as the large installations, which are housed in weather huts and are used, for example, by the German Weather Service for weather observation. Rather, these are compact models that do not require much space and are offered for use in outdoor and indoor areas. Outdoor weather stations are usually made of robust materials such as stainless steel and aluminum, whereas indoor models are often made of wood. In addition to wood, materials such as glass, metal or slate are also used.
A distinction can be made between analogueue weather stations and digital weather stations. Analogueue weather stations do not require batteries or other power sources to operate, so they will continue to operate in the event of a power failure. However, it is a disadvantage that analogueue weather stations must undergo a regular calibration. Some manufacturers recommend four calibrations per year, i.e. every quarter. In addition, analogueue weather stations are difficult for laymen to read and interpret. Digital weather stations offer more comfort in this respect. They are designed in terms of features and functions mostly more extensive. As a rule, digital weather stations are equipped with an LC display, on which the data can be read easily even without meteorological knowledge. Many models also work with pictograms (cloud with drops, sun, etc.), which make it easier to interpret the measured values. A radio controlled clock is also integrated in many cases. Digital weather stations consist of a receiver, which can be installed in the house, and an outdoor sensor, which makes permanent measurements. The recorded data are sent by the outdoor sensor to the receiver either via cable or via radio.
Buying criteria for thermometers, hygrometers and barometers – what's it all about?
First and foremost, thermometers, hygrometers and barometers must provide reliable and accurate readings. In this context, it is important to select a measuring device that is specifically tailored to the particular application. It makes a difference whether you measure the soil temperature in the garden with a fever thermometer or with a special soil thermometer. Consider which measuring task the (combined) measuring device should fulfill and decide on a model that is best suited for this purpose.
The type of execution – digital or analogue – also plays a role in the purchase and should be tailored to the application area, the level of knowledge and individual requirements. Those who regularly take measurements and want to log the recorded values should choose a high-quality digital measuring device and consider purchasing a data logger, if one is not included in the scope of delivery. Measurement data can be stored here for later analysis. If, on the other hand, you are looking for a measuring device for household use, you decide for a device with basic functions that is as simple as possible. For orientation: Analogueue thermometers are usually very easy to use and read. In order to be able to determine the values of the analogueue hygrometer and barometer, it is sometimes necessary to have prior knowledge.
Installation and mounting options should also be considered. There are thermometers, barometers and hygrometers, which are designed as table or wall devices (sometimes even wall clocks), but also those that can be attached directly to the window. Wireless or WLAN-enabled and battery-operated measuring devices are useful when several sensors should be flexibly mounted in different places.
Our practical tip: Attach thermo-hygrometer correctly
Thermo-Hygrometers are very well suited for measuring the indoor climate, but they must be placed in the right place in order to provide reliable values. In principle, thermo-hygrometer should not be placed too close to sources of cold, heat and water vapor. These include windows and exterior walls, heaters, hobs and PCs, as well as tumble dryers and bathrooms. They must not be exposed to direct sunlight, nor hidden behind curtains, but should be positioned as freely as possible in the room.
FAQ – Frequently asked questions about thermometers, hygrometers and barometers
What was relative humidity?
Relative humidity indicates the percentage of the maximum amount of water vapor in the air. It therefore refers to the ratio between the actual water vapor content and the maximum possible water vapor content. The absolute humidity, on the other hand, indicates how much grams of water a cubic meter of air contains (g/m³ ).
In which units do thermometers, barometers and hygrometers measure?
Thermometers indicate the temperature mainly in degrees Celsius (° C) and/or Fahrenheit (F), barometers measure the air pressure mostly in millibars (mbar). Some devices still use the outdated unit Torr. The relative humidity is expressed in percent (%).
What was the ideal room climate?
The indoor climate is determined mainly by the temperature and the air humidity. Indoor temperatures between 20 and 23° C are considered to be optimal in the house and apartment, whereby a role plays here in which space it is specifically concerned. In the bedroom, for example, it may well be a little cooler. Here, indoor temperatures of 17 to 20° C are often perceived as pleasant. If the air is too damp, it is necessary to avoid it in closed rooms as well as too dry air. In living and living rooms such as the children's, work or living room, a relative humidity of 40 to 60 % is ideal. In the kitchen and bathroom, whose ambient air contains more water vapor through cooking, showering and bathing, values of 50 to 60 or 70% are optimal. The same applies to cellar rooms.