HygrometerBy: Brianna and Loron

What is it?A hygrometer is an instrument used to measure

the moisture content or the humidity of the air or any gas.

This picture shows 2 types of Hygrometers showing the percent of humidity.

This picture shows the percent of humidity found in the air.

HISTORY OF THE HYGROMETER

Leonardo da Vinci built the first hygrometer in the 1400’s

Francesco Folli invented a more practical hygrometer around 1664

1783 Swiss physicist and geologist Horace Benedict de Saussure built the first mechanical hygrometer using human hair to measure humidity

John Frederic Daniell, British meteorologist and chemist invented a dew-point hygrometer in 1820 which came into world wide use not long after that

This hygrometer was invented by Francesco Folli.

How does a Hygrometer work?A simpler form of the hygrometer is a psycrometer.

It has two thermometers, one with a dry-bulb, which measures dry temperatures and one with a wet-bulb that measures wet temperatures. Evaporation coming from the wet-bulb lowers the temperature. The wet-bulb shows a lower temperature than the dry-bulb thermometer.

Humidity is determined by the temperature the dry-bulb thermometer shows. It can also be determined by the intersection of the wet-bulb and the dry-bulb temperature on a chart.

What does a Hygrometer look like?Similar to a compassThe electronic kind looks like a walkie talkie

or a blood pressure monitor

Electronic Hygrometer

Electronic Hygrometer

Types of HygrometersMechanical Hygrometers use human hair to determine

moisture content. They stretch when the humidity increases and contracts when it decreases. The human hair is attached to levers that turn the pointer on the dial.

Electronic Hygrometers measure the electrical resistance of substances. There are two types of electrical hygrometers, the Capacitance Hygrometer and the Resistance Hygrometer.

Dew Point Hygrometers use a cooled mirror to determine the temperature at which dew or frost first appears.

Chemical Hygrometers use a substance to absorb the moisture of a given volume of air

Electronic Hygrometer

Dew Point Hygrometer

Interesting FactsThere are established charts that tell the

difference between wet and dry bulb temperatures

Hygrometers are used in incubators, saunas, humidors, and museums

Chart used for HygrometersHygrometer being used in

an incubator

Works Cited http://inventors.about.com/library/inventors/blhygrometer.htm http://ask.alibaba.com/Q/800180901-what-does-a-hygrometer-look-like-.html http://support.radioshack.com/support_tutorials/weather/ws-gde-06/htm http://science.howstuffworks.com/nature/climate-weather/meteorological-instruments/hygrometer-info.htm http://www.google.com/imgres?imgurl=http://img522.imageshack.us/img522/5268/hygrometer.jpg&imgrefurl=http://expo-beauty.eu/gal/09/hygrometer-diagram%26page

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