Air density with clouds these thick and high up will change drastically. The clouds are 8304.80 m above sea level and are 21336 m thick, the total is 29640.8 meters. The half way point of the effect area is 14820.4 m above sea level. This is basically 15000 m, which has an air density of 0.1948 kg/m^3.
We use the
cloud calculator because it's able to calculate the different density levels to get a weight that is far more accurate.
Look at the weight you're getting here.
4.0589682e+18 kg is over 3.3x higher than what the actual cloud calculator got with the exact same volume of air. The weight would be lower, but the speed would become higher as less density would mean less air resistance.
I also don't see this as more accurate than my or Therefir's original calculation in the OP. To explain myself.
The initial speed of the shockwave, at least when it begins splitting, is 29640.80 m/s.
One week later, we're told that strong winds are still expecting to be felt in the USA, and is confirmed to have been caused by Izuku. Occam's Razor tells us the simplest answer is the most likely one, considering how the story is written, I'm far more likely to believe Izuku's shockwave is still moving even after one week later.
While I completely accept the idea of air resistance did slow it down, I don't accept any idea that it was significant to effect my calculation above. As I said above, even if only 1 percent of that wind speed was caused by Izuku's shockwave. Which is incorrect, because it's noticeable enough that the weather report can tell.
The difference of wind speed by the time it reaches the USA is negligible, it will always be negligible because of that detail.
The fact Izuku's shockwave is STILL producing strong winds one week later shuts down any idea that the deceleration was significant.
Note: The calculation is NOT assuming the wind speed at seal level was that fast. The wind speed above was clearly faster than the wind speed from below. Or else all of Japan and even America would've been destroyed. I'm only measuring the wind speed from over 8000+ meters above sea level. Which means any damage produced would be very minimal, as the vast majority of the energy is in the skies above.
This is why I'm actually a bit against using the Inverse Square Law here.
Considering all of these facts, no one has brought up any evidence that suggest to me that the initial speed of the shockwave would slow down massively enough to make my calculation inaccurate. The reasoning above are just over complications to something very simple.
To give an example. Let's say by the time the shockwave reached America, it decelerated to half speed as the initial shockwave.
Initial Speed = 29640.80 m/s and Final Speed = 14820.4 m/s
Distance = 10731640 meters.
Deceleration would be -30.70 m/s^2.
If this was true, the final velocity for Izuku's shockwave after just one day would be -2622839 m/s.
Which is obviously incorrect, this deceleration would mean the shockwave would've disappear. This contradicts the series, his shockwave still exist even after one week has passed. And as I said above, no one here has provided explanation to say that the strong wind wasn't caused by Izuku's air pressure.