Attention is called to a byproduct of stratospheric motion, distinct from the normal downgradient transport represented by vertical eddy diffusion. An air parcel executes a random walk over a range that could be several kilometers, and similar amplitudes could be present in wavelike oscillations. The photochemical loss rate should therefore be averaged over this range. The effect is proportional to the curvature of the profile of loss rate, and is particularly large for fluorocarbon-11, CFCl3. Test computations indicate that the known discrepancy between observations and predictions for this compound can be at least partly reconciled for plausible values of the amplitude.