The main difference between Barometer and Hygrometer is that the Barometer is a scientific instrument used to measure atmospheric pressure and Hygrometer is a instrument used for measuring the moisture content in the atmosphere.
A barometer is a scientific instrument used to measure air pressure. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems and frontal boundaries. Barometers and pressure altimeters (the most basic and common type of altimeter) are essentially the same instrument, but used for different purposes. An altimeter is intended to be used at different levels matching the corresponding atmospheric pressure to the altitude, while a barometer is kept at the same level and measures subtle pressure changes caused by weather.
A hygrometer is an instrument used to measure the amount of humidity and water vapour in the atmosphere, in soil, or in confined spaces. Humidity measurement instruments usually rely on measurements of some other quantity such as temperature, pressure, mass, a mechanical or electrical change in a substance as moisture is absorbed. By calibration and calculation, these measured quantities can lead to a measurement of humidity. Modern electronic devices use temperature of condensation (called the dew point), or changes in electrical capacitance or resistance to measure humidity differences. The first crude hygrometer was invented by the Italian Renaissance polymath Leonardo da Vinci in 1480 and a more modern version was created by Swiss polymath Johann Heinrich Lambert in 1755. Later in the year 1783, Swiss physicist and Geologist, Horace Benedict De Saussure invented the first hygrometer using human hair to measure humidity. The maximum amount of water vapor that can be held in a given volume of air (saturation) varies greatly by temperature; cold air can hold less mass of water per unit volume than hot air. Temperature can change humidity. Most instruments respond to (or are calibrated to read) relative humidity (RH), which is the amount of water relative to the maximum at a particular temperature expressed as percent.
An instrument for measuring atmospheric pressure.
Anything used as a gauge or indicator.
An instrument that measures the humidity of the air or other gases, especially the relative humidity.
an instrument measuring atmospheric pressure, used especially in forecasting the weather and determining altitude.
something which reflects changes in circumstances or opinions
"furniture is a barometer of changing tastes"
An instrument for determining the weight or pressure of the atmosphere, and hence for judging of the probable changes of weather, or for ascertaining the height of any ascent.
An instrument for measuring the degree of moisture of the atmosphere.
an instrument that measures atmospheric pressure
measuring instrument for measuring the relative humidity of the atmosphere