The irregularity of the fallout distribution is demonstrated in the figure below, which shows the fallout patterns of two separate Nevada weapons tests.

The high altitude winds of the day play a major role in determining the fallout distribution pattern. In Test 1, the winds carried fallout predominately to the north. In Test 2, the winds initially carried fallout to the west, then shifted to the northeast.

The numbers associated with each gradient of fallout represents the dose rate (in mRAD/hr) in that area.