  Weak lensing observations have the potential to be even more powerful than
cosmic microwave background (CMB) observations in constraining cosmological
parameters. However, the practical limits to weak lensing observations are not
known. Most theoretical studies of weak lensing constraints on cosmology assume
that the only limits are shot noise on small scales, and cosmic variance on
large scales. For future large surveys, shot noise will be so low that other,
systematic errors will likely dominate. Here we examine a potential source of
additive systematic error for ground-based observations: spurious power induced
by the atmosphere. We show that this limit will not be a significant factor
even in future massive surveys such as LSST.
