3. The cities listed below, from Chicago to Pittsburgh, lie in a roughly straight west to east line. Data on temperature, barometric pressure, and sky conditions for each city are shown in the table below. Use the data to explain what types of air masses are present and/or moving among these cities and how this accounts for the weather. What will Pittsburgh’s weather be like within the next 24 to 48 hours? City Temp (oF) Pressure (in.) Conditions
Chicago, IL 73 29.94 rising Clear
Indianapolis, IN 75 29.93 falling Partly cloudy
Columbus, OH 78 28.20 falling Light rain
Pittsburgh, PA 74 29.90 steady Mostly sunny

Explanation:

expect light rain in pittsburgh over the next 24 to 48 hours. The lower/falling pressures in cities to the west indicate that a low pressure system is moving from west to east toward pittsburgh. Low pressure systems are normally associated with precipitation. The fact that you do not see a big drop in temperature in the more western cities indicates the low pressure system is moving with a warm front, so only light rain would be expected. Heavy rains or more violent weather is only normally associated with cold fronts, where the warm air is pushed up and over a cold front rapidly. This rapidly rising air (convection) is what gives you heavier torrential rains, and other potentially severe weather conditions.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).