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Environmental
Day 3: Measuring air pressure

1. Atmospheric pressure is measured in millibars (mb) which is 100 newtons per square meter.
2. Two instruments used to measure atmospheric pressure are:
a. mercury barometer.
b. aneroid barometer.

mercury barometer

Fig. 1. A mercury barometer

3. Air pressure pushes on the mercury in the bottom dish, raising the mercury in the column.
4. The height of the mercury column then provides a measure of atmospheric air pressure.
5. Low air pressure will result is a shorter column.
6. High air pressure will result is a taller column.

Summary

Air pressure is measured in millibars. Barometers are used to measure air pressure.

Whizzkid Section

1. Barometers use pressure differences (differentials) to measure it.
2. The standard atmospheric pressure at sea level equals 76 centimeters (760 millimeters).
3. A pressure guage is used to measure presssure.