Reasons why the air in Delhi is worse in winter/What is cloud seeding?

Reasons why the air in Delhi is worse in winter?

• In North India, the air quality is low all year, but in winter especially after monsoon, pollution and air quality are at their worst.
• Following monsoon, the continental air mass that regularly dominates from the northwest is dry, winds calm down, and air settles stagnantly over North India.
• Cool air means that the air can hold little water vapor, and when high-pressure systems stabilize air mass, cloud cover is restrained.
• The winter hazes are not from clouds or rain, but are trapped pollution.
• Rain will occasionally occur, when western disturbances (depressions originating from Mediterranean weather systems) move across, but their frequency and timing are unpredictable.

How useful is cloud seeding?

• Simply, cloud seeding is only useful if there are existing clouds and cannot create clouds out of dry air.
• Evidence that cloud seeding produces significantly more rain than non seeding is weak and heavily contested.
• Even if cloud seeding produces rain, more than likely the pollution levels will simply rise again in one to two days.
• Framing seasonal winter smog as just a nuisance, distracts from the pollution issue occurring year-round.
• The perception of cloud seeding as a solution is an activity, much like the perception of smog towers, as being a gimmick, flashy but structurally relevant.

Risks and ethics:

• The cloud seeding occurs when silver iodide or sodium chloride is dispersed with pneumatic rockets or from aircraft, to trigger precipitation.
• The long-term effects of cloud seeding chemicals on soil and water have an uncertain impact on entire ecosystems and human health.
• If cloud seeding is the cause of flooding and/or other damage, little is known about who is accountable for costs associated with liability.
• Public perception can erroneously frame or layer cloud seeding into every heavy rainfall conversation.

What is cloud seeding?

This is a method to try to increase precipitation by releasing chemical compounds such as sodium chloride or silver iodide into a cloud.

How it works:

Silver iodide has a crystalline structure that resembles ice. The crystal induces water droplets to freeze and precipitate as either rain or snow.

Limitations:

1. Cloud seeding requires pre-existing clouds from which to make rain—it cannot generate clouds from dry air.

2. The evidence for increasing precipitation consistently through cloud seeding is weak and contested.

3. Any effect of rain on reducing pollution is always temporary, frequently lasting only 1-2 days.

Risks:

1. The long-term effects on soil and water from the chemicals used in cloud seeding are unknown, as the chemicals may accumulate in them.

2. Cloud seeding could result in flooding among other unforeseen consequences, and liability is unclear.

3. Cloud seeding misleads the public and has potential to distract from real solutions to pollution.

Ethical issues:

1. Cloud seeding is viewed as an apparent “shortcut” rather than targeting the root causes of air quality pollution.

2. It is possible that validating cloud seeding with science could lead to wasted resources and diminished trust in science and government.