3 ms·

Like Fujita scale for Tornados, it's about potential for potential damage it can cause which is here dependent somehow on the wind speed variable. I'm sure some

Like Fujita scale for Tornados, it's about potential for potential damage it can cause which is here dependent somehow on the wind speed variable. I'm sure someone more knowledgeable about it can explain how it's correlated, but it's not about wind speeds (alone).

lcnPylGDnU4H9OF 3y ago
Reminded of a joke by Ron White in the context of a person choosing to remain behind in a hurricane because they believe they can withstand the wind and rain: “It’s not that the wind is blowin’, it’s what the wind is blowin’.” On topic, it makes me wonder if the wind cutoffs have to do with what can be additionally picked up by the increase in energy. I’d honestly assume not but I would still hesitate to assume that it’s arbitrary. Not really sure but the phrasing of the joke made me wonder.
- Keyframe 3y ago
  This made me interested as well. Why the exact cut-offs, right? I found few resources like NOAA https://www.nhc.noaa.gov/pdf/sshws.pdf https://www.nhc.noaa.gov/pdf/sshws.pdf and wikipedia https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale saying basically about the wind speed that the actual wind speed is "sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height" and then I thought ok if this scalar we're using is correlated to potential damage, that would mean force, right? They did remove air pressure and storm surges as components later on. I didn't bother with air pressure outside of standard since it would deviate a lot into researching exactly that. Since it's not really my domain, I decided to wing it by googling around and looked for wind force formulas. One that I found out ( https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wind-force-increases-as-the-square-of-the-velocity/#:~:text=The%20Force%20on%20a%20unit,F%20%3D%20r%20V%5E2 https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wi.... ) can roughly be translated as F = v^2 but then when I charted it out with x being wind speed and y proportional force, only thing I found out was that it looked logarithmic (which I didn't need a chart for lol ). The other I found was saying for wind load formula "The generic formula for wind load is F = A x P x Cd where F is the force or wind load, A is the projected area of the object, P is the wind pressure, and Cd is the drag coefficient." I had to hunt for variables here, but gist of it is that since scale is in mph I went USA with 1 square foot for A - area (and then to square meters from that, 0,093 m^2), wind speed to m/s, and went with these (more googling): Wind Pressure (P) is P = 0.5 x p x V^2 where p (rho actually) is air density (google: 1.225 kg/m^3 at sea level and 15C, I couldn't find one at 10m height), V is our wind speed, and Cd (drag coefficient) for a flat plate which is 1.28 according to https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/shaped.html#:~:text=A%20flat%20plate%20has%20Cd,07%20to%20 https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/a.... tl;dr; I couldn't find clear cuts in Newtons. I tried minimum, maximum and average wind speeds for each categories, and then I kind of lost interest there. More googling says that it was based on established observations what wind force can do to structures, but no more than that and I couldn't source original work to see more details. Outside of optics, this is as far as my physics will lead me tonight. I'd be highly interested to see if anyone more in the know can provide methodology behind it, be it from meteorology, construction, or fluid dynamics.
- kurthr 3y ago
  Yeah, you know that's not a bad idea... just label the Category by what is being blown around in the wind. Category 1: Trash Cans and Patio Furniture Category 2: Shingles and Gardening tools Category 3: Branches and Bricks Category 4: Small vehicles and mobile homes Category 5: Lage vehicles and houses Category 6: Full concrete Trucks and and Roads I once traveled ('97) to go see the damage done by an F5 tornado and what struck me was that a 50ft wide section of asphalt roadway had been removed where the eye had passed. Granted that is about 270mph, but I would still be worried about depressurization even in a bomb shelter.
  - Pikamander2 3y ago
    Category 7: Hospitals and skyscrapers Category 8: Small continents Category 9: Other hurricanes Category 10: Your mom
    - gct 3y ago
      You're getting downvoted but this gave me a chuckle
genocidicbunny 3y ago
The thing I find interesting (in a way) is that even then, the damage caused is not a single-variate function. Where I live, we just had a massive for the area storm with really strong wind gusts. My little weather station on my balcony recorded 80mph gusts. I also have several new cracks in the walls from when the roof tried to leave the building. But in other places, hurricanes and tornadoes much stronger than that still end up leaving buildings intact. We try so hard to reduce so many things to a single number, a single qualifier. And nature just keeps showing us why that's not entirely useful. Musings from an evening spent in the dark, and perhaps the slightly spoiled leftover meatloaf that I had because there was no power to cook anything.

lcnPylGDnU4H9OF 3y ago

Reminded of a joke by Ron White in the context of a person choosing to remain behind in a hurricane because they believe they can withstand the wind and rain: “It’s not that the wind is blowin’, it’s what the wind is blowin’.” On topic, it makes me wonder if the wind cutoffs have to do with what can be additionally picked up by the increase in energy. I’d honestly assume not but I would still hesitate to assume that it’s arbitrary. Not really sure but the phrasing of the joke made me wonder.

Keyframe 3y ago
This made me interested as well. Why the exact cut-offs, right? I found few resources like NOAA https://www.nhc.noaa.gov/pdf/sshws.pdf https://www.nhc.noaa.gov/pdf/sshws.pdf and wikipedia https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale https://en.wikipedia.org/wiki/Saffir%E2%80%93Simpson_scale saying basically about the wind speed that the actual wind speed is "sustained winds as average winds over a period of one minute, measured at the same 33 ft (10.1 m) height" and then I thought ok if this scalar we're using is correlated to potential damage, that would mean force, right? They did remove air pressure and storm surges as components later on. I didn't bother with air pressure outside of standard since it would deviate a lot into researching exactly that. Since it's not really my domain, I decided to wing it by googling around and looked for wind force formulas. One that I found out ( https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wind-force-increases-as-the-square-of-the-velocity/#:~:text=The%20Force%20on%20a%20unit,F%20%3D%20r%20V%5E2 https://sites.uci.edu/energyobserver/2017/09/07/hurricane-wi.... ) can roughly be translated as F = v^2 but then when I charted it out with x being wind speed and y proportional force, only thing I found out was that it looked logarithmic (which I didn't need a chart for lol ). The other I found was saying for wind load formula "The generic formula for wind load is F = A x P x Cd where F is the force or wind load, A is the projected area of the object, P is the wind pressure, and Cd is the drag coefficient." I had to hunt for variables here, but gist of it is that since scale is in mph I went USA with 1 square foot for A - area (and then to square meters from that, 0,093 m^2), wind speed to m/s, and went with these (more googling): Wind Pressure (P) is P = 0.5 x p x V^2 where p (rho actually) is air density (google: 1.225 kg/m^3 at sea level and 15C, I couldn't find one at 10m height), V is our wind speed, and Cd (drag coefficient) for a flat plate which is 1.28 according to https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/airplane/shaped.html#:~:text=A%20flat%20plate%20has%20Cd,07%20to%20 https://www.grc.nasa.gov/www/k-12/VirtualAero/BottleRocket/a.... tl;dr; I couldn't find clear cuts in Newtons. I tried minimum, maximum and average wind speeds for each categories, and then I kind of lost interest there. More googling says that it was based on established observations what wind force can do to structures, but no more than that and I couldn't source original work to see more details. Outside of optics, this is as far as my physics will lead me tonight. I'd be highly interested to see if anyone more in the know can provide methodology behind it, be it from meteorology, construction, or fluid dynamics.
kurthr 3y ago
Yeah, you know that's not a bad idea... just label the Category by what is being blown around in the wind. Category 1: Trash Cans and Patio Furniture Category 2: Shingles and Gardening tools Category 3: Branches and Bricks Category 4: Small vehicles and mobile homes Category 5: Lage vehicles and houses Category 6: Full concrete Trucks and and Roads I once traveled ('97) to go see the damage done by an F5 tornado and what struck me was that a 50ft wide section of asphalt roadway had been removed where the eye had passed. Granted that is about 270mph, but I would still be worried about depressurization even in a bomb shelter.
- Pikamander2 3y ago
  Category 7: Hospitals and skyscrapers Category 8: Small continents Category 9: Other hurricanes Category 10: Your mom
  - gct 3y ago
    You're getting downvoted but this gave me a chuckle

genocidicbunny 3y ago

The thing I find interesting (in a way) is that even then, the damage caused is not a single-variate function. Where I live, we just had a massive for the area storm with really strong wind gusts. My little weather station on my balcony recorded 80mph gusts. I also have several new cracks in the walls from when the roof tried to leave the building. But in other places, hurricanes and tornadoes much stronger than that still end up leaving buildings intact. We try so hard to reduce so many things to a single number, a single qualifier. And nature just keeps showing us why that's not entirely useful. Musings from an evening spent in the dark, and perhaps the slightly spoiled leftover meatloaf that I had because there was no power to cook anything.