More hail stones 5 mm diameter

[Walter]

There is a very heavy down pour of hail stones 5 mm diameter again in Winnersh, they are bouncing over a foot off the ground.

[Steve]

Walter,

We've had them here in Ruislip too.

They seem to expect snow in the coming weeks.

I see Las Vegas is around 90 and expecting 100f Monday - time for a US meet perhaps...

Steve

[Walter]

Another Hail Storm.

I think they should change the saying from April Showers to April Hail Stones.

[Roger]

I think 5mm is the maximum for a droplet that freezes and falls as 'ice'. More than that size of vapour would separate and form as two or more droplets. I'll have to read up on it again!

[Steve]

I noticed on the news there was talk of hail the size of gold balls in Florida in recent weeks.

A China story on golf ball hail killing three on Sky News here, with video: http://news.sky.com/home/world-news/article/16206718

..Sky News also has stories on French golf ball hailstones from last year, with lots of damage reported.

We've had a lot of hail, more like pea size or less here though. They are talking of enough rain for floods in the coming days.. I do hate these droughts...

Steve

[Walter]

I was in Reading yesterday and it was just very light rain but Winnersh which is just 3 miles away there was a heavy hail storm.

Just shows how localised the weather is.

[Roger]

I think 5mm is the maximum for a droplet that freezes and falls as 'ice'. More than that size of vapour would separate and form as two or more droplets. I'll have to read up on it again!

Having read more ;-) It appears that an 'updraught' can play a part ...keeping the droplets aloft until coalesence of freezing droplets makes bigger frozen droplets that stay aloft until they are too heavy to be sustained there by the force of the updraught, then falling to the ground at whatever size they amassed whilst being suspended by the updraught. Interestin' stuff this!

[Coops]

I noticed on the news there was talk of hail the size of gold balls in Florida in recent weeks.

A China story on golf ball hail killing three on Sky News here, with video: http://news.sky.com/home/world-news/article/16206718

..Sky News also has stories on French golf ball hailstones from last year, with lots of damage reported.





We've had a lot of hail, more like pea size or less here though. They are talking of enough rain for floods in the coming days.. I do hate these droughts...

Steve

I studied Aviation Meteorology for a while in my past and I seem to remember that the size of the hail stones are proportional to the vertical extent of the storm cloud. To build higher and higher storm clouds we need a constant supply of warm moist air feeding in from the bottom to create updraughts. This moisture can then freeze when it gets high enough because temperature drops with altitude, if it is kept aloft by the updraughts it will form hail as described by Roger.

So why don't we get golf ball sized hail? The answer is that cloud tops are limited by the height of the Tropopause (the level where the temperature stabilizes and it will not get any colder). In the UK that is at about 36000 feet; you can see it clearly because the cloud will flatten out sideways and form the characteristic 'anvil' shape. That's why airlines can fly in smooth air above the storms. In the tropics the air is much warmer so the tropopause is higher, sometimes up above 60,000 feet, this combined with very warm air at the bottom feeding up creates much bigger, taller and much more violent storms. These in turn create more dramatic weather like giant hailstones and tornadoes to suck in more air from below.

Isn't it good to live in a mild climate?