1. Hygrometer By: Brianna and Loron

2. 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.

3. 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.

4. 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.

5. What does a Hygrometer look like? Similar to a compass The electronic kind looks like a walkie talkie or a blood pressure monitor Electronic Hygrometer Electronic Hygrometer

6. Types of Hygrometers Mechanical 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 Dew Point Hygrometer Electronic Hygrometer

7. Interesting Facts There 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 Hygrometers Hygrometer being used in an incubator

8. 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