A barometer is a scale that measures the “weight” of the atmosphere. The scale is in inches of mercury on the outer circle, and millibars on the inner circle. This instrument should be kept inside. A typical reading will be near the value of 30 – 31 inches of mercury. Readings of higher values are associated with high pressure and fair weather conditions. Lower values are associated with low pressure and messy weather conditions. To better understand how lower pressure values/measurements are associate with messy weather, it is important to compare values taken/observed at the same time each day, and observed for several weeks

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