Students Seminar Series
13th October 2003
- Collision and Coalescence
- Ice Crystal Process
Typical warm Clouds
“A method used to precipitate solute from the solvent - Pieces of solid material placed in a supersaturated solution to promote precipitation of the dissolved solute”
There are three types of cloud seeding: static mode, dynamic mode, and hygroscopic seeding.
Alter the microphysical
Properties of clouds
Attempt to modify the
Air motion within the clouds
Use of hygroscopic material to
Obtain the intended result (eg: salt)
Static or Dynamic
Warm Cloud Seeding
Cold Cloud Seeding
Cumulus Clouds having cloud top temp < 0oC
To increase population of water drops
To increase population
of ice crystals
Seeding with Silver Iodide
Sodium Chloride or Urea
Formation of Rain through Hygroscopic Seeding
Examples of Hygroscopic Material
Objective of Hygroscopic Seeding
Introduce large drops into cloud
Large drops collide with small cloud droplets and grow into rain drops (Coalescence)
Rain drops heavy and large enough to fall out of cloud and reach ground.
It can be distributed from the ground...
…or from the air.
Automated High-Output Ground Seeding System
Cloud Seeding Aircraft
A hole in a stratus cloud deck due to cloud seeding with aircraft, using dry ice
This is where super cooled cloud droplets are converted into ice crystals
, which then precipitate out of the cloud deck.
Thank You aircraft, using dry ice