A atmospheric thermometer is a device that measures the temperature of the indoor or outdoor atmosphere. The most common type consists of a long tube that contains mercury or colored alcohol at the base, although there are also other kinds, such as spring and digital thermometers. When the atmospheric temperature rises, it causes the material inside the air thermometer to expand. Conversely, when the air gets colder, the material contracts and travels back down.Thermometers use temperature scales either Fahrenheit, Celsius, Kelvin, to provide a measure of heat in degrees.
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Atmospheric thermometer Wikipedia(Text) CC BY-SA