Question

Artificial rain is produced by spraying cloud with
A) Calcium chloride
B) Sodium chloride
C) Aerosoles
D) None of these

Answer 1

Hint: Artificial rain is the method of cloud seeding, which is a kind of weather modification. The aim of the cloud seeding is to change the amount of precipitation that falls from the clouds. This can be done by dispersing substances into the air.

Complete answer:
Cloud seeding is the method of modification of the weather. In this process, the artificial rain is produced by spraying dry ice or silver iodide aerosols into the upper part of the cloud and trying to stimulate the precipitation and form rain. The stimulation can be done by using aeroplane and rocket. The most commonly used substance is silver iodide because it is cheap and easily available.
The cloud seeding can be done in three stages, they are as follows:
Agitation: In this stage, the chemical is used to stimulate the air mass upwind of the target site to rise and form clouds. The chemical absorbs the water vapour from the air and helps in the condensation process. A chemical such as calcium oxides, ammonium nitrate, chloride, calcium carbonate.
Building upstage: This is the second stage, in this step the mass of the cloud is built up by using dry ice, urea, salts (kitchen salt) to increase the density of the clouds.
Seeding: In this super cool chemicals are bombarded with pressurised canisters at the base of the clouds to build the water droplets beads. Finally, make them fall as rain.
Following are the types of cloud seeding methods:
Hygroscopic cloud seeding: In this method, the salts are dispersed via flares or explosives in the lower part of the clouds. The salts molecules join with water and grow in size.
Static cloud seeding: This involves the spraying of the chemical like silver iodide into the air/cloud. The silver iodide provides a crystal around it, so that moisten can condense.
Dynamic cloud seeding: Here, the vertical air current is a boost, this leads to the more water to pass through the clouds.

Note: The precipitation or enhancement of rainmaking was first done in 1946 when American scientist Vincent Schaefer and Bernard Vonnegut at general electric were successful cloud seeding is done by using dry ice.