WMOD00008

• Applicant: Colorado Greenhouse Inc.
• Project Name: Colorado Greenhouse Inc.
• Date: 6/12/1998
• Weather Modification - Doc Type: Record of Decision

"SIMPLIFIED" DEVELOPMENT OF HAIL STONE

A hail stone forms from what has to be . a small rain drop. As this rain drop is falling -
relative to air speed, (updraft can and will suspend it in altitude but it still has the same
effect). As it's falling it will start to freeze. This is not an instantaneous freezing, but
rather a progressing from the outside inwards, logically the inside is insulated from the
cooling effect of the air. The build up in diameter is caused by the collisions with other
super cooled droplets. These droplets' whose temperature is ,150C and lower, "NOT
FROZEN" won't freeze until they attach or contact either a dust particle or an already
formed ice particle,

This is how the stone grows,' "no doubt they also sweep up occasional ice particles -
but this is certainly a minor mechanism of growth,'"

The fre'ezing of super cooled droplets colliding with a hailstone liberates heat. As a
supercooled droplet freezes, it's temperature rises to zero C. Only wh~~_a.Il!I:!~v...aleI _ __
- - - - - - --iF\-the-dr~pteHreezes;-caniheiempera:rol'e again ta:Jl1l8!ow zero. -

This heat liberation, while some of it is external to the atmosphere, most will transfer to
the more dense mass of the hailstone - thereby helping to keep it warm - rather than
creating a super cooled stone. Only when the building process stops can the stone get
colder, by then it's on it's way down and into a different environment.

Moderately
eto"ll

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falll"ll &
cooline

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falll"ll&
cooU"lI

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Solid HaU.ton.

51mpllflod ~.Iopm.nt of tull1lltonll

12

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