Figure 9-5.—The Schrader gauge.to all hands. We plan or cancel operations on thebasis of weather predictions. Accurate weatherforecasts are made only after a great deal ofinformation has been collected by many observerslocated over a wide area.One of the instruments used in gatheringweather data is the barometer, which measuresair pressure. Remember, the air is pressing on youall the time. Normal atmospheric pressure is 14.7psi. As the weather changes, the air pressure maybe greater or less than normal. Air from high-pressure areas always moves toward low-pressureareas, and moving air—or wind-is one of the maincauses of weather changes. In general, as airmoves into a low-pressure area, it causes wind,rain, and storms. A high-pressure area usuallyenjoys clear weather. Ships use two types ofbarometers to measure air pressure: aneroid andmercurial.Figure 9-6.—Diaphragm pressure gauge.9-5
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business