1. Here's what I did...create a new Paint.Net doc.
2. Click on the circle select and draw a circle by holding down shift.
3. Change your primary color to white and your secondary color to a dark brown.
4. Click on Effects>Clouds. Turn the scale down a bit...the lower the scale the smaller the cloudy area...I used 184 and 50.
5. Once clouds are on, add noise via the Effects>Add noise menu...I used 64 and 0.
6. Motion blur that the direction you want it to go...I used 141 degrees and 22 px.
7. Adjust the Brightness/Contrast under adjustments...I used -72 and 58.
8. Gaussian blur @ 2 px.
9. Add a layer of black/white clouds and set layer blending to overlay.
By playing around with these settings, I'm sure you'd be able to make something close to that. Does this help at all?