Smaller-sized hail is common in Western Massachusetts during severe weather events. Thunderstorms that produce hail, are also known as hailstorms. Hail is formed when the updrafts of developing and maturing thunderstorms are particularly strong and persistent. A little known feature of thunderstorms, is that the rising, condensing air into liquid water usually rises above the freezing line, and becomes ice pellets (this is not the same classification as sleet). However, there is so much warm air just below this coldest top layer, that all of the ice pellets melt on the way down to the surface, coalescing, and growing larger into the big raindrops we see in the downpours from thunderstorms.
However, in particularly persistent and longer-lived updraft formations, these frozen raindrops can be suspended for long enough in the freezing layer of air, that they coalesce into larger hailstones, and fall to Earth as ice. Hail also tends to form when these freezing layers descend lower towards the surface of the Earth. These areas of downdrafting hail are called “hail cores”, and an odd green or other coloring can be present in the skies of severe thunderstorms that feature hail, and even tornados.
Hailstones, during their upward journey, can pass through alternating areas of dense supercooled water droplets and water vapor. It is thought that this is the reason they develop their layered composition of translucent and opaque ice. Hailstones also collide into each other, and can accrete more ice this way as well. Eventually, they become too heavy in relation to the updraft that spawned them, and they fall to the Earth’s surface.
Hail in Western Massachusetts severe weather events tends to stay pretty small, around pea-size, but they can grow larger than that in some severe cases.
Hail is different than sleet, as sleet forms in the Winter when liquid rain falls through a thicker cold layer at the surface of the Earth, which freezes the rain droplets into ice pellets before landing on the ground.