Rain crusts tend to be much smoother than sun
crusts. Unlike sun crusts, rain crusts form uniformly
on all aspects but rain crusts--like rain--is highly elevation
dependent. Typically rain falls at lower elevations and as you
ascend through the freezing level the rain progressively turns
Prolonged rain on new snow forms drainage channels down the
fall-line and make a corrugated pattern in the surface snow.
These drainage channels (also called "rill marks,"
are a strong sign of stability).