Question

Which of the following is used in seeding clouds?
A. Potassium iodide
B. Silver iodide
C. Mercuric chloride
D. Both A and B

Answer 1

Hint:- Clouds are formed when water vapours in the atmosphere reach its saturation point. It can be achieved either through evaporation or by condensation process in the atmosphere. Different types of precipitation fall down from the clouds when the size of the condensing water droplets reaches its maximum. Seeding of clouds is the artificial method for changing the amount of precipitation falling down from the clouds.

Complete step-by-step solution:-
Cloud seeding aims at changing the type or quantity of the precipitation falling down from the clouds in the form of snow, rain or hailstorms. This can be done with the help of certain chemicals that are similar to ice such as dry ice or solid carbon dioxide, potassium iodide, silver iodide etc.
Clouds are formed when water vapours condense around dust particles called condensation nuclei. By cloud seeding, the number of condensation nuclei is increased which thereby helps to increase the precipitation of the water vapour in the cloud.
Static seeding method is used in mid altitude clouds and dynamic seeding is used in the cumulonimbus clouds in warm tropic regions. The dispersal of cloud seeding chemicals is done either by air crafting or through instruments placed on the ground, the former being more effective. It is believed that the cloud seeding method is effective and can increase the precipitation rate in the atmosphere. Silver iodide is more effective as its structure has close similarity with that of ice crystals.
The correct answer is Option D- Both A and B.

Note:-
Cloud seeding was invented by a chemist, Vincent. J. Schaefer. Cloud seeding methods are said to be effective but have adverse effects on the environment. The uptake of elementary silver can be harmful to organisms and can increase the rate of algal blooms but chemists claim that silver iodide does not have an effect on living organisms.