The Clouds In A Polluted World

Clouds are an essential part of the environment for world temperature and the water cycle; in a polluted world, their functions are diminished and can even be harmful.

The chemicals present in the air influence the clouds; therefore, air pollution will also be part of the cloud as composition; tiny water droplets or ice crystals mostly made up the clouds. 

Temperature changes can favor the condensation of water in clouds; when these drops of water become too heavy to remain suspended in the cloud, they fall to Earth as rain; some types of clouds produce precipitation, while others do not.

Image 1: The chemical composition of the air and the environmental conditions of each region are factors in the formation of clouds.

A well-known effect of environmental pollution is acid rain, caused by the deposition of dangerous pollutants in clouds; includes the spread of acids, such as sulfuric or nitric acid; this can comprise rain, snow, fog, hail, or even acid dust.

Every cloud needs a condensation core, a particle of dust, dirt, volcanic ash, sand, or sea salt; These cores attract the water vapor; and as they rise, the water condenses according to altitudes to give the different types of clouds as a result.

What is the role of the clouds?

Clouds can reflect incoming rays from the sun into space, cooling Earth. Or they can trap heat near the Earth's surface, warming the planet. That is why the chemical composition is so relevant since this will assign a majority function.

For clouds to form, the ground must be warmer and the air cooler so that soil moisture can evaporate, rise, and condense higher in the atmosphere.

The formation and growth of clouds can also be affected by smoke and other pollutants, as it reduces the temperature gap between the earth and the air, forcing more abrupt changes to generate the clouds.

Smoke and other pollutants absorb the temperature emitted by the soil and the sun; this heats the air and carries currents of hot air through the earth's atmosphere. Favors global warming, causing the water on the ocean surface to heat up and evaporate into the atmosphere.

As the main reservoir of water in the water cycle, the oceans are related to climate exchanging water with the atmosphere. Consequently, due to global warming, this cycle currently tends to accelerate and causes more frequent extreme weather events such as rains, droughts, or cyclones.

The world's water is distributed approximately according to the following percentages (these numbers tend to change with new environmental conditions): Atmosphere 0.001%, Glaciers and frozen layers 1.9%, Earth 0.1%, Ground-water 0.6%, oceans 97.5%. See Image 2.

Image 2: Water distribution on the planet.

The role of smoke and daily activities influences the air pollution in clouds and rain. By looking specifically at deep convective clouds, tall clouds like storm clouds, formed by rising warm air, the studies show that smoky air makes it difficult for these clouds to grow. On the other hand, the pollution may energize the growth, but only if the pollution isn't heavy. Extreme pollution is likely to halt the growth of clouds.

In the Australian wildfires, the smoke cooled the Earth by blocking some solar radiation, causing marked cooling in ocean areas where the clouds are not usual. However, climate change results in more fires at high latitudes in the future

A possible scape

Scientists from the Indian Meteorological Department (IMD) say continued cloudy conditions and improved wind speed are likely to keep the air clean. The University of Waterloo team has confirmed that "pyrocumulonimbus" clouds can remove pollution into the stratosphere.

So maybe you thought that it would be convenient to alter the atmospheric opacity with the clouds to cool the planet; unfortunately, global food crops could be affected with their yields affected.

The changes in sunlight due to the scattering and absorption of clouds are consistent between crops and regions, which means that the seasons expose them to cycles of similar conditions.

Some plants can have higher yields with more light; optimal cloudiness increases corn and soybean yields by 0.4%. Changes in sunlight due to changes in clouds result in reduced world yields of corn and soybeans by 1% and 0.1% due to air pollution and could increase by a loss of 1%, 8%, and 0.4% if we add the effects of climate change.

Some countries and regions have adopted 'cloud seeding' to try to beat the drought caused by global warming by adding small amounts of silver iodide, a chemical compound that so far seems safe. Cloud seeding is an inexpensive way to add water to watersheds and help localities where water is scarce. There is a question as to whether this will be able to do in the future conditions of a changing climate: you need cold temperatures, and once it is too hot, you cannot do cloud seeding.

Image 3: Cloud seeding is an increasingly common practice.

Global warming and environmental pollution had led to the search for other solutions to fight the caused effects. One includes intentionally increase in a controlled manner the concentrations of aerosols (pollutants) over the oceans, with safe chemical compounds that manage to cool the planet due to the improvement in reflectivity associated with a decrease in the size of the droplets and would contribute to a cooling of the earth's surface. 

This previous solution can complicate the situation because it can cause an increase in the number of clouds at low levels of the atmosphere and even cause a reduction in the drizzle.

"It's about the complexity in dust type, color, and size; Sahara dust may be lighter, while dust from an Asian desert might likely be darker. A blanket of lighter-colored or smaller dust scatters incoming sunlight while not warming the air. Larger or darker dust particles absorb sunlight and warm the air." Said Jonathan Jiang of NASA's Jet Propulsion Laboratory in Pasadena, California. Referring to the fact that the chemical composition of the clouds is responsible for modifying the heating/cooling effects to the environment in global warming and environmental pollution.

References

• Ocean & Climate Platform. From the Ocean to the clouds. A healthy ocean, a protected climate. https://ocean-climate.org/en/awareness/from-the-ocean-to-the-clouds/

• Zamri, Muhamad Najib & Sunar, Mohd Shahrizal. (2019). Research on Atmospheric Clouds: A Review of Cloud Animation Methods in Computer Graphics. 10.1109/ICRAIE47735.2019.9037755. 

• E&E News. Chelsea Harvey. Why cloud seeding won't reverse climate droughts. Wednesday, March 17, 2021. Link https://www.eenews.net/stories/1063727677

• Proctor, Jonathan. (2021). Atmospheric opacity has a nonlinear effect on global crop yields. Nature Food. 2. 166-173. 10.1038/s43016-021-00240-w. 

• The Guardian. Oliver Milman. Make it rain: US states embrace 'cloud seeding' to try to conquer drought. Tue 23 Mar 2021 09.30 GMT. Link https://www.theguardian.com/environment/2021/mar/23/us-stated-cloud-seeding-weather-modification

• New Scientist. Donna Lu. Recent Australian wildfires led to record atmospheric pollution. Environment 18 March 2021. Link https://www.newscientist.com/article/2271829-recent-australian-wildfires-led-to-record-atmospheric-pollution/.

• NASA. Carol Rasmussen. NASA study untangles smoke, pollution effects on clouds. Sep 24, 2018. Link https://www.jpl.nasa.gov/news/nasa-study-untangles-smoke-pollution-effects-on-clouds.

• Scientific American. Gayathri Vaidyanathan. How Does Air Pollution Affect Clouds?. ClimateWire on June 6, 2014. Link https://www.scientificamerican.com/article/how-does-air-pollution-affect-clouds/

• The University of Waterloo. New research shows certain clouds remove air pollution from the surface of the Earth. Wednesday, August 12, 2020. Link https://uwaterloo.ca/science/news/new-research-shows-certain-clouds-remove-air-pollution.

• Shah, J. & Nagpal, T. & Johnson, Todd & Amann, Markus & Carmichael, Gregory & Foell, Wesley & Green, Charles & Hettelingh, Jean-Paul & Hordijk, Leen & Li, J & Peng, C & Pu, Y. & Ramankuttyl, R. & Streets, D.. (2000). Integrated analysis for acid rain in Asia : Policy implications and results of RAINS-ASIA model. Annual Review of Energy and the Environment 25 (2000). 25.