GEO101 Earth Science
Colorado State University Global
The creation of the barometer is largely attributed to Evangelista Torricelli, an Italian physicist and mathematician (Rubin, 2018). Torricelli had questioned if air was truly weightless and wanted to test out this theory. Using a liquid heavier than water, Torricelli experimented with mercury in a vacuum and confirmed that the weight of air in the atmosphere caused the liquid to stop falling (Rubin, 2018). Barometers are used to measure air pressure and are most commonly used to predict weather forecasts. A glass tube sealed at one end is filled with mercury and is then inverted in a small cup called a cistern (Rubin, 2018). This will cause the mercury to spill slightly into the cistern and create a vacuum at the sealed end of the tube. It is the atmospheric pressure on the mercury that sits in the cistern is what keeps the rest of the mercury in the tube (Rubin, 2018). The height of the mercury in the tube can be measured to interpret the atmospheric pressure.
A thermometer is an instrument that measures temperature. The first reliable thermometer was invented in 1714 by Daniel Gabriel Fahrenheit (Benedict, 1984). Though thermometers have been seen as far back as 70 AD, it wasn’t until Fahrenheit used mercury that the instrument provided some consistency and was widely adopted by the world (McGee, 1988). Thermometers are designed to measure temperature using a sealed tube that is partially filled with mercury. As the temperature around the thermometer increases, the mercury begins to expand and rise up the tube (Benedict, 1984). The tube has markings on it to indicate the temperature in Fahrenheit or Celsius.
A rain gauge measures how much rain has fallen during a storm. Made from a graduated cylinder, a rain gauge simply needs to be placed outside during a storm, free from anything that may prevent the rain from being collected. The Greeks were the first to measure rain and keep rainfall records and throughout history, the rain gauge has been altered to what we see today (Strangways, 2010). The collection and recording of rain measurements is one way that scientists can determine how much water has fallen over an area. It can also help meteorologists and farmers recognize weather patterns and prepare for any upcoming weather changes (Dragini, 2019).
A hygrometer measures water vapor, or humidity, in the air (Bellis, 2019). It was Leonardo da Vinci who built the first one in the 1400’s, and since then the hygrometer has had many transformations. Humidity can be determined by a number of tests but with the hygrometer two thermometers are used. One of the thermometers is a “wet bulb” and the other is a “dry bulb” (Gorse, Johnston & Pritchard, 2012). The wet bulb is simply a thermometer with a moist cloth wrapped around the bottom. As the moisture begins to evaporate from the cloth, the temperature of that thermometer will change. When you compare the temperature reported on the wet bulb to the one on the dry bulb and the differences between the two can give a relative idea of the humidity (Gorse et al., 2012 ).
Weather vanes have been seen throughout history as far back as 139 BC (Needham & Ling, 1959). They seem to have been invented in ancient China and Greece, independently of each other, around the same time (Needham & Ling, 1959). Mostly used as decoration today, the wind vane is used to determine the direction the wind is coming from. The construction of a wind vane is rather simple, consisting of a rod with an arrow on one end to show direction while the other end has a wide ornamental decoration designed to catch the wind. The rod is able to spin, and when wind is caught, it spins the arrow in the direction that the wind is blowing from (Needham & Ling, 1959).
An anemometer is an instrument that measures wind speed and pressure (National Geographic Society, 2012). The device is rather odd looking, consisting of three or more cups that are meant to catch the wind and spin. As the wind blows it spins the cups and based on how fast it spins scientists are able to determine the speed of the wind (National Geographic Society, 2012). Created during the 15th century by Leon Battista Alberti, the anemometer has hardly changed. Wind speeds help indicate changes in weather patterns and can help meteorologists determine if a storm is approaching (National Geographic Society, 2012). Additionally, knowing wind speed is very important to pilots and even engineers.
Bellis, Mary. (2020, February 11). The History of the Hygrometer. Retrieved from https://www.thoughtco.com/history-of-the-hygrometer-1991669
Benedict, R. P. (1984). Fundamentals of temperature, pressure, and flow measurements. 3.ed (3rd ed.). Wiley.
Dragani, R. (2019, November 22). Why Is a Rain Gauge Important? Sciencing. https://sciencing.com/rain-gauge-important-6611576.html.
Gorse, C.; Johnston, D.; Pritchard, M. (2012). A Dictionary of Construction, Surveying, and Civil Engineering. Oxford Quick Reference. OUP Oxford. p. 960. ISBN 978-0-19-104494-6.
McGee, T. D. (1988). Principles and methods of temperature measurement. Wiley.
National Geographic Society. (2012, October 9). anemometer. National Geographic Society. https://www.nationalgeographic.org/encyclopedia/anemometer/.
Needham, Joseph; Ling, Wang (1959), Science and Civilisation in China: Mathematics and the Sciences of the Heavens and the Earth, Vol. 3, Cambridge University Press, p. 478
Roveti, D. K. (2001, July 1). Choosing a Humidity Sensor: A Review of Three Technologies. FierceElectronics. https://www.fierceelectronics.com/components/choosing-a-humidity-sensor-a-review-three-technologies.
Rubin, J. (2018). Evangelista Torricelli The Invention of the Barometer. Retrieved June 24, 2020, from https://www.juliantrubin.com/bigten/torricellibarometer.html
Strangeways, I. (2010). Precipitation: theory, measurement and distribution. Cambridge University Press.
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