When and where does convectional rain occur?

How does Snow and Freezing Rain occur?

• I understand that it always rains when the temperature is above 32 degrees Fahrenheit. When it's below 32 degrees does it snow? Or does freezing rain occur? When do both Snow and Freezing rain occur?

• Answer:

  Snow forms as a particle of condensation nuclei passes through air which has supercooled water molecules in suspension by the wind. As the particle passes through, water droplets hit the particle and instantly condense and freeze. As the drop grows, it picks up more and more water until it can no longer be held in the wind, upon which it falls. Freezing rain occurs when a large above freezing air mass is wedged in between two subfreezing air masses vertically. The droplet initially forms as snow, melts through the warm air mass into rain, and then freezes on contact as it hits the subfreezing surface. It does not need to be below 32 at the surface for it to snow. Snow can hold its shape up to 34-36F - they will be very large, wet flakes, potentially aggregates, where the needles on the flakes interlock into a mess. However, it is relatively hard for flakes to survive above that temperature. Freezing rain actually occurs when temperatures are slightly above freezing but the surface is below freezing. A subfreezing air mass would mean sleet, or refrozen rain (snow is not frozen rain, contrary to popular belief). It is very, VERY hard for both rain and snow to fall at the same time, because it would incur that the air mass would both have sufficient melting and nonmelting potential. Freezing rain is, after all, rain. It just depends on the surface temperature.