I have a science question that I'm hoping somebody here can help me with.
How can hail stay in the sky?
I heard how hail the size of grapefruit fell in the U.S. last week, but how does it stay in the sky long enough to become the size of grapefruit.
I believe the biggest hail stones have an up and down journey, getting caught in updrafts as they fall and accumulate weight and size.
the biggest hail that I've ever seen was bigger than a golf ball, but I have family and friends that have experienced larger. quite an amazing event.
A chunk of ice the size of grapefruit weighs a lot, I'm wondering how much wind would be needed to keep all of that flitting about in the sky.
I wish there was a way we could see that.
See, if a couple of feet of snow falls, it's easy for me to imagine mist, then flakes being blown about in the sky for miles up, flakes weigh very little. I can even see it in my mind's eye.
But hail, even golfball-sized, seems too heavy to be blown about for a very long time. I can't picture it. Especially since hail is roundish.
If hail was flat, shaped like a frisbee for example, then it being buffeted about would be easy to understand, but a lump wants to come crashing down to the ground. Gravity insists upon it and it's shape keeps it from sailing on drafts.
well, here's from the Wikipedia:
Quote:
Hail is a type of graupel, a form of precipitation, composed of spears or irregular lumps of ice. It occurs when supercooled water droplets (remaining in a liquid state despite being below the freezing point, 0°C/32°F) in a storm cloud aggregate around some solid object, such as a dust particle or an already-forming hailstone. The water then freezes around the object. Depending on the wind patterns within the cloud, the hailstone may continue to circulate for some time, increasing in size. Eventually, the hailstone falls to the ground, when the updraft is no longer strong enough to support its weight.
Hail
never heard of graupel.
Here's some specific speed-size correlations:
http://www.tornadoproject.com/safety/hail.htm
Even more interesting to me was when I read for the first time that all precipitation starts as ice - so rainfall was originally hail, in effect, before melting on descent through warmer air!
Here's a nice little summary page on precipitation and fog
http://www.physicalgeography.net/fundamentals/8f.html
>>55+ mph to create hail the size of a golf ball, and an updraft of 90+ or more mph to create hail the size of a baseball.
Huh. If I think about it, I've been through some windstorms - one just recently - where I've had trouble walking and I've seen small cars being pushed across the street and a truck blown over. I don't recall exactly, but I think it was at 120km/h.
I guess, if the wind is pushing up, then a golfball-sized, or even a grapefruit-sized chunk of ice would be blown upwards instead of downwards.
Thanks guys, that easier to visualize.
The largest hail ever reported, IIRC, was on the "lee" side of the Himalayas, and was large enough to actually kill a couple of elephants. I think it was described s being close to basketball or soccer ball size.
Hail tends to be larger and more prevalent on the lee side of mountain ranges, a phenomenon I saw many times while living in Colorado. One storm dumped fist sized hail that actually built up and pushed a house off its foundations somewhere between Denver and Boulder. Don't remember whether it was Louisville or Broomfield, but I remember the pictures in the RM News.
Here's a pretty good scientific explanation, bel:
web page
"The Cloud" by Percy Bysshe Shelley
I wield the flail of the lashing hail
And whiten the green plains under,
And then again I dissolve it in rain,
And laugh as I pass in thunder.
