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River Science: Barometric Pressure

Barometric pressure is also known as air pressure or atmospheric pressure. Simply put, it represents the weight of the air above us. Just as water pressure increases as you dive deeper beneath the surface, barometric pressure drops as you rise in altitude (and thus have less air above you). Of more immediate importance, barometric pressure is a valuable indicator of weather conditions; rapidly dropping barometric pressure typically means that stormy weather is on its way.

Captain Hudson would have loved to possess a barometer in 1609; although the connection between air pressure and the weather was intuitively understood in his day, the first instrument to measure it would not be invented until 1643.

The barometric pressure remained fairly steady during our data layover in East Haddam, but the same could not be said of the Half Moon's shakedown voyage to New London or the opening days of this Voyage of Discovery, when a pocket of low pressure hanging over Long Island Sound contributed to waves of cold fronts, dense fog, and rain.

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