Hail stones in July !!
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max_tranmere
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Hail stones in July !!
It's been pissing with rain here in London for about 30 minutes, and in the last 5 minutes it has started hailing!! Thousands of mini ping-pong balls landing and bouncing all over the path outside where I live. And this is July not January! It's mid-summer! Has global-warming caused this?
Re: Hail stones in July !!
Do you want to buy an Air Con Unit as it is due to heat up again ... one careful owner.!cool!
Works A Treat!!!wink!
Works A Treat!!!wink!
PEOPLE think Stephen Hawking is so clever, but when you ask him a question and he is typing in the answer on his little screen, how do we know he isn't just looking up the answer on the Internet?
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max_tranmere
- Posts: 4734
- Joined: Fri Jul 14, 2017 2:40 am
Re: Hail stones in July !!
No thanks, I don't mind the heat. By the way the rain, now hail, is coming down so hard here in London that the TV reception has gone. I can't get any channels. Looks like an evening of DVD's tonight!
Re: Hail stones in July !!
All Hail the Stones! Hail the Stones!
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Mysteryman
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- Joined: Fri Jul 14, 2017 2:40 am
Re: Hail stones in July !!
Hailstones are more a summer than winter phenomenon. They form in cumulo-nimbus clouds in which the convective currents move them around rapidly.
They start as water droplets which are forced into the supercooled air at the top of the anvil heads in the CB clouds and then fall quickly, often rising again and gaining size and weight. Due to the power of the convective currents, most hailstones remain in cloud layers without falkling to earth and eventually melt as the cloud warms up.
Certain temperature/pressure combinations allow them to fall to the bottom of the cloud layer and, if they have reached a certain weight, they can fall to earth.
The more violent the convective currents, the more likely it is that the down side of the pressure gradient will allow hail to descend rapidly and fall to earth fast enough that it will not melt into rain after passing through the freezing level (say around 5000 feet) and thus become apparent as anything from a light hail shower to damaging hail, such as the massive golf ball sized examples seen, for instance, in the US midwest during the tornado season.
Large hail showers have been around as long as man has kept his eye on the weather and, in themselves, have nothing to do with global warming - there are centuries old records of hail damage in the UK for instance, but the frequency and severity of sharp, localised, thunderstorms does seem to be currently increasing.
They start as water droplets which are forced into the supercooled air at the top of the anvil heads in the CB clouds and then fall quickly, often rising again and gaining size and weight. Due to the power of the convective currents, most hailstones remain in cloud layers without falkling to earth and eventually melt as the cloud warms up.
Certain temperature/pressure combinations allow them to fall to the bottom of the cloud layer and, if they have reached a certain weight, they can fall to earth.
The more violent the convective currents, the more likely it is that the down side of the pressure gradient will allow hail to descend rapidly and fall to earth fast enough that it will not melt into rain after passing through the freezing level (say around 5000 feet) and thus become apparent as anything from a light hail shower to damaging hail, such as the massive golf ball sized examples seen, for instance, in the US midwest during the tornado season.
Large hail showers have been around as long as man has kept his eye on the weather and, in themselves, have nothing to do with global warming - there are centuries old records of hail damage in the UK for instance, but the frequency and severity of sharp, localised, thunderstorms does seem to be currently increasing.
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max_tranmere
- Posts: 4734
- Joined: Fri Jul 14, 2017 2:40 am
Re: Hail stones in July !!
Mysteryman - interesting.
Re: Hail stones in July !!
Was that on The Burke Special?
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Mysteryman
- Posts: 878
- Joined: Fri Jul 14, 2017 2:40 am
Re: Hail stones in July !!
No, it's basic meteorology.