Barometric Pressure and Hurricanes
Hurricane Michael is bearing down on the panhandle of Florida and is said to be the strongest hurricane to hit the panhandle of Florida since 1894, around 134 years ago. While Michael is an extremely dangerous storm that will undoubtedly cause major damage to the area, there have been a number of other hurricanes in that 134 years as strong and some stronger than Hurricane Michael.
Hurricanes impacting the eastern United States are caused by storms often originating near or over the west coast of Africa. The storm moves over warm sections of the Atlantic where the water heats the air above it causing the air to rise. This rising air causes the barometric pressure in the area to decrease and air from outside rushes in to replace the rising air. The air starts to circulate around the storm due to a phenomenon called the Coriolis effect which deflects the incoming air to the right in the northern hemisphere and to the left in the southern hemisphere.
In the northern hemisphere the Coriolis effect obeys what in engineering is called the "right hand rule". The air at the center of the storm is moving upward due to the heating from the Atlantic Ocean water, with your right hand point your thumb upwards (the direction of the air movement) and the wind rotates in the direction your fingers are pointing. A similar, but luckily less dangerous, situation occurs when a toilet when flushed. The water is going down and the water in the bowl rotates in the direction of your right hand fingers. I suppose in the southern hemisphere they would have to use the "left hand rule".
As the sea water continues to heat the air it continues to rise decreasing the barometric pressure and increasing the Coriolis effect causing the winds to rotate around the storm at higher and higher speeds. Standard barometric pressure is 29.92 inches Hg (mercury) and there is no requirement of a barometric pressure for a Category 1 hurricane. Another way atmospheric pressure is measure is with millibars where 1000 millibars is normal atmospheric pressure (29.92 inches Hg). Below is a table showing the various category levels of hurricanes and the atmospheric pressure requirements and wind speeds.
Hurricane Intensity | Atmospheric Pressure | Wind Speed |
---|---|---|
Category 1 | 28.94 inches Hg or more 967 millibars or more | 74 to 95 mph |
Category 2 | 28.5 to 28.93 inches Hg 952 to 966 millibars | 96 mph to 110 mph |
Category 3 | 27.91 to 28.49 inches Hg 933 to 951 millibars | 111 mph to 130 mph |
Category 4 | 27.17 to 27.90 inches Hg 908 to 932 millibars | 131 mph to 155 mph |
Category 5 | less than 27.17 inches Hg less than 908 millibars | greater than 155 mph |
The only barometric pressure reading I could find for Hurricane Michael is 933 millibars making it a borderline Category 4 hurricane, it is expected to make landfall as a Category 4. Hurricane Michael is going to be a pretty elite class when compared to other relatively recent hurricanes. Some hurricanes most will remember of similar intensity include Irma (2017), Sandy (2012), Wilma (2005), Rita (2005), and Katrina (2005). Let's all just hope the residents of the Florida panhandle heeded to calls to evacuate to get out in time.
Hurricanes are one of the most destructive natural disasters we can have. It's no comfort to understand that hurricanes are simply one of the earth's natural methods of dissipating energy. The real unfortunate part of this process is when we humans get in the way.
Sources:
Michael Strengthens to an 'Extremely Dangerous' Category 4 Hurricane
Reference: Wind Speed to Storm Surge
Understanding Barometric Pressure in Hurricanes
Hurricane Michael: Pressure DROPS to TERRIFYING low - Florida told 'We CANNOT SAVE YOU'
They are all disasterous, yes.
The reports from those affected areas are a testament to Mother Nature. You don't mess with Mother Nature.
Not sure how I would react if we faced a natural disaster here. Can't imagine. I wish them well down there.
I learned somethinng once again. And another badge....nice accomplishment.
You have enough snow that to them would be a natural disaster.
Thanks, I just don't understand the benefit of the badges.
I look at the badges for fun and because I didn't have to sign up for anything. Lol
I don't think they attribute to any statistics or reputation score, etc.
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