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What happens inside a cloud?
Making Rain Remember what is needed for rain to form in a cloud: For "warm rain", raindrop formation relies on collision and coalescence, which requires a high concentration of liquid water and a wide spectrum of droplet sizes. In cold clouds, the most important processes are ice crystal formation and vapor diffusion which was discussed in Ice Crystal Formation, both requiring initial growth of an ice embryo.
What if we could insert ice or
condensation nuclei into a
a cloud? This would
give the supercooled water in the cloud a better chance of freezing or
condensing, and maybe it would increase the precipitation from the cloud.
Scientists have been trying to enhance precipitation in drought-prone areas and
in regions with high water demands through such a process, called cloud seeding.
In warm clouds, calcium chloride is often used to provide the nucleus for
raindrop formation. In cold clouds, silver iodide is used because its structure
is very similar to that of an ice crystal. The seeding can take place from the
ground or from airplanes.
Next page
->
Making Rain continued
Links and resources
Making Rain Remember what is needed for rain to form in a cloud: For "warm rain", raindrop formation relies on collision and coalescence, which requires a high concentration of liquid water and a wide spectrum of droplet sizes. In cold clouds, the most important processes are ice crystal formation and vapor diffusion which was discussed in Ice Crystal Formation, both requiring initial growth of an ice embryo.
What if we could insert ice or
condensation nuclei into a
a cloud? This would
give the supercooled water in the cloud a better chance of freezing or
condensing, and maybe it would increase the precipitation from the cloud.
Scientists have been trying to enhance precipitation in drought-prone areas and
in regions with high water demands through such a process, called cloud seeding.
In warm clouds, calcium chloride is often used to provide the nucleus for
raindrop formation. In cold clouds, silver iodide is used because its structure
is very similar to that of an ice crystal. The seeding can take place from the
ground or from airplanes.
Next page
->
Making Rain continued
Links and resources
