So in the new movie Thor creates a storm that covers the whole of Asgard.
Darkanine already calculated the radius of Asgard; 4,088.56m
I will use a real Cumulonimbus cloud as a basis, since they are responsible for the vast majority of storms.
3300 / 101 = 32.6732673
32.6732673 x 420 = 13722.7723
Cylinder volume = pi x r^2 x h
pi x 4088.56^2 x 13722.7723 = 7.20663424e11 cubic metres.
7.20663424e11 x 1.003 = 722825414272kg.
Since the cloud is forming lets half that to find the KE of one piece.
361412707136kg.
Radical assured me it happened in a second.
KE = 0.5 x 4088.56^2 x 361412707136 = 3.02074575e18 Joules.
Since that's only one of the two piece's let me double it to account for the other.
So for Thor forming the cloud we get 6.0414915e18 Joules or 1.44395112 Gigatons.
High 7-A. I was hoping for 6-C so it would be more consistent with Surtur destroying Asgard, but this is how it is I guess. Although if someone could find a picture of the actual storm cloud that would make the calc even better.
Darkanine Version[]
Actually now that I think about it, maybe horizon distance can be used instead? Chris Hemsworth is 6′3, so 1.9 meters
That would make the Horizon 4.9 km
pi * 4.9^2 = 75.429 km^2
75.429 * 13 = 980.577 km^3
So 9.80577e+11 m^3
9.80577e+11 * 1.003 = 983,518,731,000 kg
4.9 km / 1 second = 4,900 m/s
983,518,731,000 * 0.5 *4,900^2 = 1.1807142e+19 J
2.8 Gigatons. Slight improvement.