Cloudscapes and Climates: The Dynamic Interplay of Aerosols, Forests, and the Atmosphere
Part 3: Contrasting High and Low Cloud Systems
As we continue our atmospheric journey, let's delve into the contrasts between the high cloud systems formed from dust particles and the low cloud systems influenced by forest aerosols. This comparison highlights the diverse and complex interactions within our planet's climate system.
The previous post in the series can be accessed here;
High Cloud Systems: The Dust Particle's Influence
Dust particles, particularly those larger than 60 to 80 nanometers, are vital in forming high cloud systems. Often found at altitudes above 6 kilometers, these clouds are composed of smaller water droplets or ice crystals due to the abundance of cloud condensation nuclei provided by dust. They can spread over large areas, merging with other cloud systems and influencing weather patterns across vast regions. These high-altitude clouds impact Earth's energy balance significantly. While they reflect sunlight and can have a cooling effect, they also trap heat, contributing to the greenhouse effect and global warming. The intense, heavy rainfall they release leads to significant erosion and flooding.
Low Cloud Systems: The Forest's Contribution
In contrast, forests release Biogenic Volatile Organic Compounds (BVOCs), contributing to the formation of low-cloud systems. Typically found at lower altitudes, often below 2 kilometers, these clouds are characterized by larger raindrops due to the forest's emissions. They play a crucial role in maintaining regional climate stability, contributing to a more regular and gentler precipitation pattern, which benefits the ecosystem.
Mountains influence cloud formation and weather patterns. Mountains up to 6,500 feet typically capture low cloud systems, while those towering at 20,000 feet or more elevations, such as the Himalayas and Karakoram, catch nearly all cloud systems.
This explains why regions with low forest cover, like Pakistan, experience most rainfall in higher mountainous areas. The Himalayas and Karakoram create “cold deserts” behind them by blocking moisture from the oceans and cloud systems, earning the nickname "the third pole." This phenomenon of rain blocking is called “rain shadow”.
The Atmospheric Ballet: A Comparison
The contrast between high clouds, formed from dust particles, and low clouds, influenced by forest aerosols, illustrates the dynamic nature of Earth's atmosphere. High clouds, part of a global climate system, largely influence weather patterns and contribute to broader climate change issues like global warming. Low clouds, more localized, directly impact the climate and ecology of their surrounding areas.
In Conclusion, The Interconnected Climate System
Our exploration of high and low cloud systems reveals the intricate balance within Earth’s atmospheric system. Each type of cloud plays a distinct role in shaping our global climate. High clouds, though contributing to global warming, are essential for understanding large-scale weather patterns. Low clouds, crucial for regional climate stability and ecological health, are influenced by local factors such as forest cover and mountainous terrain.
Stay tuned for our next lecture, where we'll explore more fascinating aspects of Earth's climate system and the myriad factors that make it.
References
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Twomey, S. (1977). The influence of pollution on the shortwave albedo of clouds. Journal of the Atmospheric Sciences, 34(7), 1149-1152. Link
Boucher, O., Randall, D., Artaxo, P., Bretherton, C., Feingold, G., Forster, P., ... & Zhang, X. Y. (2013). Clouds and Aerosols. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Link
Andreae, M. O., & Rosenfeld, D. (2008). Aerosol-cloud-precipitation interactions. Part 1. The nature and sources of cloud-active aerosols. Earth-Science Reviews, 89(1-2), 13-41. Link
The Third Pole Environment (TPE)." This is an international program focused on the Tibetan Plateau and surrounding mountain ranges, often referred to as the Third Pole due to their extensive ice fields.
Mountain Ranges and Climate: How Topography Influences Weather." This resource would provide insights into how mountain ranges like the Himalayas and Karakoram influence local and regional climate systems.
Website: National Geographic Resource Library