The Marshall-Palmer raindrop size distribution (inverse exponential shape, constant intercept) was established for low rain rates by Marshall and Palmer [1948], and has been found to apply to a variety of precipitation and air circulation conditions. The development of this distribution was shown by Young [1975] to be a result of nucleation, condensation, coalescence and especially breakup. Zawadzki et al. [1994], however, have recently cast doubt on this interpretation, especially for low rain rate conditions. They extended the model of Valdez and Young [1985] to allow raindrops to fall relative to the air through sedimentation, and showed that for low rain rate conditions the Marshall-Palmer distribution does not develop, but rather a time evolving spectral shape that was steeper than Marshall-Palmer near cloud top and flatter than Marshall-Palmer near middle sizes (0.2-0.8 mm diameter) at cloud base. These results were in good agreement with orographic rain observation in Hawaii. Their results suggest that breakup of drops is not important for these low rain rates, as advocated by Young [1975], but rather drops grow by direct collisional growth. Thus, these results suggest that the Marshall-Palmer distribution does not hold for warm rain size distributions at low rain rates. Zawadski et al. [1994] also present observations from a melting snowfall situation that is consistent with a Marshall-Palmer size distribution for the melted snowflakes, and suggest that only under melting snow conditions can one use the Marshall-Palmer size distribution for characterizing the raindrop size distribution at low rainfall rates. This result suggests that one needs to carefully consider the use of the Marshall-Palmer size distribution in bulk cloud microphysics parameterizations when low rain fall rates are simulated.