What are the differences between the conditions that lead to lake effect snow versus ocean effect snowfall? Both can lead to significant snowfall, but usually lake effect causes large snow amounts.
Well, for one is the salination. The salt in oceans lowers the vapor pressure, lowering the evaporation rates (i.e. the salinated water is hindered from evaporating).
Another is the amount of fetch. Over a large enough ocean, the air is modified by the surface temperature of the water. With a lake, the amount of surface is usually not as great, so the air is not warmed as much by the lake. That is, the classification of the air that causes lake effect snow is continental polar (cP) or Arctic (A). However, ocean-effect snow is most like maritime polar (mP), which tends to be more mild. One instance where this tends to not be a major factor is Japan’s snow country, where the fetch from the Sea of Japan tends to be optimized for snow.