We need to start up in the clouds, which are made up of water vapour. Tiny specks of dust cause the vapour to condense into drops of water which may then fall out of the cloud as rain. But sometimes, the drops get blown upwards inside the clouds and freeze. More water condenses on them, and the frozen drop grows. This can happen many times. If you can keep a hailstone frozen for long enough to cut it open you can see the layers built up from each trip up through the cloud. Eventually it becomes too heavy to stay up any more, and falls as a hail stone.
Many hailstones melt before even reaching the ground. The ones that do reach the ground vary in size from tiny to quite large. I remember a hail storm in Queensland (I saw the results, but was fortunately not there when it happened) where the hailstones were large enough to break a large plate-glass window in the airport and leave “pock-marks” 2-3 centimeters across in the bark of trees. The hail-stones were reported to be as large as golf balls.
Usually, they are from 1 to 3 millimeters in diameter.
I don’t think I can add much to Peter’s answer – we had a massive hail storm in Melbourne here a couple of years ago on Christmas Day in 2011 – heaps of cars damaged. Take a look at some of the pictures: http://bit.ly/14ilFmZ – hail stones as big as chicken eggs!!!
We need to start up in the clouds, which are made up of water vapour. Tiny specks of dust cause the vapour to condense into drops of water which may then fall out of the cloud as rain. But sometimes, the drops get blown upwards inside the clouds and freeze. More water condenses on them, and the frozen drop grows. This can happen many times. If you can keep a hailstone frozen for long enough to cut it open you can see the layers built up from each trip up through the cloud. Eventually it becomes too heavy to stay up any more, and falls as a hail stone.
Many hailstones melt before even reaching the ground. The ones that do reach the ground vary in size from tiny to quite large. I remember a hail storm in Queensland (I saw the results, but was fortunately not there when it happened) where the hailstones were large enough to break a large plate-glass window in the airport and leave “pock-marks” 2-3 centimeters across in the bark of trees. The hail-stones were reported to be as large as golf balls.
Usually, they are from 1 to 3 millimeters in diameter.
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I don’t think I can add much to Peter’s answer – we had a massive hail storm in Melbourne here a couple of years ago on Christmas Day in 2011 – heaps of cars damaged. Take a look at some of the pictures: http://bit.ly/14ilFmZ – hail stones as big as chicken eggs!!!
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