Atmospheric Speckle Statistics

What you are seeing: a short-exposure stellar image through atmospheric turbulence. The pattern has $N \sim (D/r_0)^2$ speckles, each of size $\sim \lambda / D$ . Re-roll to see different realizations: the ensemble follows negative-exponential intensity statistics.

Figure 1. Short-exposure speckle pattern.

D / r_06.0

WHAT TO TRY

Raise D/r_0 for stronger turbulence over a bigger aperture: the short exposure boils into more and finer speckles, each a diffraction-limited image of the star scrambled in phase.
Watch the histogram lock onto p(x) = exp(-x): fully developed speckle has a negative-exponential intensity, with contrast sigma over mean equal to one.
Compare short and long exposure: averaging many speckle frames washes them into the smooth seeing disk, the blur that speckle imaging and adaptive optics exist to beat.