What is cloud seeding?

Question

and does it have an affect on the environment?

Answer 1

Cloud seeding is an attempt to enhance rainfall by introducing condensation nuclei into a convective cloud at a level where there is an abundance of liquid water droplets that are below freezing.

Dry ice and silver iodide are the most common chemicals used now but at one point many different compounds were used and even lead iodide was used (not a good choice). You can see that it could be bad environmentally if some of the compounds were used but CO2 and silver iodide are thought to be safe.

The though of the process was to increase the freezing of the liquid water and thus release the latent heat of fusion and increase the buoyancy of the cloud which should increase the updraft and continue the process of making rain.

The process is controversial to many because it does introduce something into the atmosphere and that it needs to be near raining conditions for the process to work anyway.

So, there is always the question if it would have rain that much without the cloud seeding? That is hard to answer because after you seed a cloud, how don't know if it would have rained that much or not if you had done nothing.

Answer 2

Condensation of water vapour in the atmosphere produces clouds.But,water vapour requires what is called condensation nuclei to produce the clouds.These condensation nuclei are usually available in the atmosphere in the form of dust particles,salt particles,droplets of sulphuric acid smoke etc.So, the water vapour condenses on these nuclei and form tiny water droplets.The concept of codensation nuclei has led to the idea of cloud seeding that tries to encourage rainfall by seeding the air with condensation nuclei appropriately.
Even though many nuclei are available in the atmosphere and water droplets are formed over these nuclei,very few water droplets grow in size and become rain drops.So, to increase the rain drops and thereby produce rain,formation of more water droplets shoud be encouraged and ,for that, we require more condensation nuclei.To achieve this, cloud seeding is done.
Silver iodide and dry ice(frozen CO2) are the chemicals used for cloud seeding.Salt is also added as it has affinity for water and thereby becomes ideal nuclei.

Answer 3

Cloud seeding is a method of artificially coaxing rain out of the clouds with silver iodide and / or dry ice.

Answer 4

Wikipidia has a great answer for this:
LOL What Jduck said