posted on Jun, 25 2017 @ 03:31 AM
a reply to: randyvs
Hail is created within supercell storm clouds. These have really strong updraughts and downdraughts that feed the 'snowflake like' ice crystals around
and around in cycles.
These cyles occur entirely at altitudes where the temperature is below freezing. The ice crystal structures grow larger and colder but are very
filamentous and light like super light, super low density, snowflakes, but bigger, less dense and more 'clumpy'.
Towards the top of the supercell, the ice/air structure becomes very cold. Not only the ice crystals but also the air trapped inside becomes
supercooled and this is then cycled back down. When at the bottom of the supercell, these ultra cold structures stick to each other and also
crystallize more ice.
If the updraught is strong enough, it takes the structure back up to cool more, becoming larger and larger with each circuit, but at some stage, the
mass of the ice/air clump falls away from the supercell cycle and falls.
On the way down, the outer parts of the ice/air clump liquefy briefly, condensing on the super cold core. The outermost layer stays liquid but the
inner layers are cold enough to re-freeze the liquid water. Additionally the ultra cold clump condenses extra water from the warmer lower atmosphere,
building up the bulk of what rapidly becomes a ball of ice, as it falls.
Strangely enough, it is those ultra hot conditions at ground level, that usually cause the most powerful supercell storm clouds.
After heatwave days while I was living in Sydney Australia you'd get these supercell clouds that had an intensely greenish colour and most times, the
rain would include hail. The more intensely green the clouds, the more likely big hail.