This document provides a history of meteorology and summarizes the invention and purpose of several key weather instruments: - A minimum-maximum thermometer records the highest and lowest temperatures over 24 hours to measure greenhouse temperatures. - An aneroid barometer measures air pressure changes to indicate approaching rain or storms. - A sling psychrometer uses wet and dry bulb thermometers to measure relative humidity by comparing temperatures. - A special barometer was built for Pennsylvania counties to study meteorology using funds from the state legislature. - An anemometer measures wind speed using a ball pendulum moved by wind pressure.

1. HISTORY OF METEOROLOGY

2. The word 'meteorology' was coined from a research book called 'Meteorologica' which was written by Aristotle, a Greek scientist and philosopher. This early work described the science of earth like its geology, elements, hydrology, seas, wind and weather. In the modern term, the term meteorology explains a complete science. It is for understanding the dynamics of atmosphere and forecasting weather phenomena like hurricanes and thunderstorms. Weather forecasting was practiced since the beginning of time with more or less accuracy. Historical records show several examples of weather predicting methods based on observing surrounding elements. Sky is undoubtedly the first indicator used in meteorology its cover and nature of clouds provides clues of the upcoming temperature and weather. The wind factor is also important and is associated with temperature and often rains. Animals and birds are also known to give indications about the future weather. Scientists across the world since ancient times have tried to understand the meteorological phenomena like wind and rain. Many instruments for measuring wind power, humidity and rain were invented in the early 15th century. During the 17th century, several discoveries tipped in favor of scientific meteorology. A device to measure temperature was invented by Galileo Galilei and the factor that atmospheric pressure was linked to altitude was discovered by Blaise Pascal. The invention of barometer by Evangelista Torricelli is significantly the most important discovery. It is still in use today which indicates atmospheric pressure changes that are linked with the future weather changes. There are also other methods which have been evolved. Meteorology is a lot related with cycles and their analysis which was what Fernando II de Medici wanted to prove. He carried out a very determined program in 1654 for recording weather patterns in different European cities with a view to compile data and make their analysis. Other breakthroughs were followed in the 18th century and science was taken to a new level. A modern mercury based thermometer was invented by Gabriel Fahrenheit. Theories about hydrodynamics were devised by Daniel Bernoulli and those theories had helped greatly in understanding the atmospheric changes. When the theory of thermodynamics and atmospheric pressures were adapted, no real changes were important for understanding meteorology. In recent times, focus has been given on meteorological tools for its improvement and attaining better accuracy results. A tremendous boost was given to meteorology because of the technology in two ways. The first is the ability to communicate results and analysis with timing, it was made possible due to the invention of telegraph. The second is the ability of probing skies with using balloons, satellites and radars. Meteorology is a part of our everyday lives. People are kept updated about the changing weather with dedicated channels and mobile devices. The science is still progressing and is an important element of the economy with many industries like agriculture and civil aviation depending on it.

3. INVENTION OF WEATHER INSTRUMENT

4. This weather instrument is called a Minimum-Maximum thermometer. It is used to record the highest and lowest temperatures observed over a 24-hour period. There are many uses for a minimum-maximum thermometer; one example would be to measure how low the temperature dropped in a greenhouse overnight to figure out exactly when it gets too cold for the plants or flowers to survive. This particular thermometer was made by W.H. Kessler Co., Inc.

5. Aneroid barometers are instruments used for measuring the pressure of the air in the atmosphere. They weren't invented until the 1840s—years after Franklin's time. High or rising pressure means that clear, sunny weather is expected, while falling or low pressure is a sign of rain or an approaching storm. As air pressure increases, it pushes down on a metal diaphragm, which in turn causes the indicating needle to move. This aneroid barometer was made in Germany and sits on an octagonal wooden base.

6. A sling psychrometer, the simplest type of hygrometer, measures the relative humidity of the surrounding air by comparing the temperatures of one dry and one wet bulb thermometer. A small chain on the end of the wooden handle attaches the thermometers to each other. The psychrometer is spun around rapidly for a few minutes and readings are taken from the dry and wet bulbs. After these readings are taken, there is a scale that is used to correlate the readings. The relative humidity is read at the intersection of the RH scale and the wet bulb temperature.

7. This barometer shown below is a very special piece in The Franklin Institute's collection. It was built especially for the Museum with funds provided by an Act of Legislature (March 31, 1837) that authorized the spending of $2,000 for work in meteorology and the purchase of instruments for each county of the state of Pennsylvania. (There was an additional $1,000 expenditure for each of the two following years.) The barometer is 42 inches tall, and has a mercury thermometer on it. The inscription reads: "Furnished to Philadelphia City by the Joint Committee of Meteorology of the American Philosophical Society and the Franklin Institute of Pennsylvania by the Authority of the State of Pennsylvania." It was made by L.C. Francis, Philadelphia.

8. Thermometer The anemometer pictured above is a modern version of Robert Hooke's 1667 anemometer, a device Benjamin Franklin was probably familiar with. An anemometer is a device used for measuring wind speed. The pressure of the wind moves the aluminum ball pendulum and the velocity of the wind is read from the scale. This instrument is 14.5 inches tall and was a part of The Franklin Institute's weather center for many years.