I keep seeing that Hurricane Milton has record pressure but I don’t understand it. What does pressure of 905 mb mean and why is it important for understanding the size and scale (and potential devastation) of a hurricane?
In: Planetary Science
Air has weight. You don’t notice it, but each square inch of you body has about 15 (14.7) pounds of air pushing in on you if you were at sea level. Because the wind blows, the amount of weight of the air changes from day to day (or even hour by hour). The amount of air weight is called barometric pressure.
It was origonally measured by filling a glass tube full of mercury and turning it upside down. They measured how high the mercury filled into the tube. You can actually do the same with water, but you need about a 3 story building. The average was around 30 inches and ultimately the “standard” was set at 29.92 which is still used today for airplanes and pilots. Metric system came along and they set the standard to 1000 millibars (which was later adjusted to 1013).
Low pressure systems tend to draw moisture and wind into them with resulting storms. High pressure pushes wind and moisture away resulting in hot dry weather.
Hurricanes are extremely low pressure systems where the low pressure correlates to high winds and high storm surge. 905 is VERY low and only is found in the strongest hurricanes ever recorded.
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