Just a do over of the Sonic Rainboom Calculation that was apparently deleted. Should be a quick enough calc. Feat ca be found here.
The door is 297 Pixels. Average height of a door is 6'8, so 2.07264 Meters. Pinkie is 83 Pixels.
297 / 83 = 3.57831325301
2.07264 / 3.57831325301 = 0.57 Meters
That gives a Horizon distance of 2.7 Kilometers. This is a low end, I'll use the more standard 4.8 Kilometers as a high end.
This is a first person shot. All of that used to be cloudly and dreary, but is not sunny and cloudless.
Since the clouds go on forever back, I will be using 2.7/4.8 as a radius. So times those by two to get a proper diameter.
2.7 * 2 = 5.4
4.8 * 2 = 9.6
Using area of a square.
S = s^2
5.4^2 = 29.16 km^2
9.6^2 = 92.16 km^2
So these clouds have a thickness of 12 Kilometers on average.
Volume = area * thickness
29.16 * 12 = 349.92 km^3 (3.4992e+11 m^3)
92.16 * 12 = 1105.92 km^3 (1.10592e+12 m^3)
Density of Clouds: 1.003 kg/m^3
3.4992e+11 * 1.003 = 350,969,760,000 kg
1.10592e+12 * 1.003 = 1.1092378e+12 kg
Low Ball Timeframe
The Rainboom happens to start dispersing clouds at 18 Seconds in, ends at 24 seconds.
24 - 18 = 6s
5.4 km / 6s= 900 m/s
9.6 km / 6s = 1600 m/s
KE = M * 0.5 * V^2
350,969,760,000 * 0.5 * 900^2 = 1.4214275e+17 Joules
33.9 Megatons of TNT
1.1092378e+12 * 0.5 * 1600^2 = 1.4198244e+18 Joules
339.3 Megatons of TNT
This timeframe assumes to scenes are happening at once. The one where Pinkie first sees the Rainboom ad when it speeds up. Happens from 22 seconds to 24 seconds, so 2s. Obviously, this may be a bit to assumption happy.
5.4 km / 2s = 2700 m/s
9.6 km / 2s = 4800 m/s
350,969,760,000 * 0.5 * 2700^2 = 1.2792848e+18 Joules
1.1092378e+12 * 0.5 * 4800^2 = 1.2778419e+19 Joules
Final Tally and Power-Scaling
Low-Low End: 33.9 Megatons
Low-High End: 339.3 Megatons
High-Low End: 305 Megatons
High-High End: 3 Gigatons
I believe Dash was at the Epicenter of this, so it should scale to her durability. It's consistent with the other 7-B/7-A to 6-C feats in the series, so I wouldn't consider it an outlier.