In 2023, pollutants released in New York can reach the air over Iceland in just 4 days. Hundreds of years ago, in 1883, ash from Indonesia's Krakatau volcano eruption landed approximately 10,000 miles away in New York within 13 days.
These are two nice examples to illustrate the point that we all share the same air. Air moves through the atmosphere in predictable currents at a rate of ~500 meters/second (close to 1,000 miles/hour!). The air we breathe is a shared resource that transcends geographical boundaries and impacts the well being of the entire planet. It's a dizzying concept, but important to understand because this is how carbon dioxide molecules emitted in one part of the world get mixed up with those emitted in other parts of the world. More importantly, it’s why carbon dioxide is sucked from the air in one part of the world - say, Iceland! - reduces the overall atmospheric concentrations that benefit us all, no matter where we live. If you're curious about how all this works, here’s what you need to know about atmospheric circulation.
Atmospheric circulation is driven by solar energy, Earth’s rotation, and features of Earth’s surface such as mountains and valleys, rivers and bodies of water. Due to the position of the Earth in relation to the sun and its spherical shape, more solar energy reaches the equator than the north and south poles. We’ve all heard the phrase hot air rises, right? The warm air at the equator rises and flows to the cooler polar regions. The cool air will then sink and move back towards the equator. This pattern is called convection and it creates global wind patterns. It’s no coincidence that our convection ovens are named after the same concept. The fans inside of a convection oven induce air circulation creating a more efficient heating system.
The second major element to atmospheric circulation is the Coriolis effect. Our earth spins on its axis from west to east - this is why the sun appears to set in the west and rise in the east. This rotation causes the air traveling between the poles and the equator (convection currents), to deflect. This means that air moving away from the equator curves to the right in the northern hemisphere and to the left in the southern hemisphere. There are three types of convection cells, Hadley cells, Polar cells, and Ferrel cells (learn more here) that create a continuous mixing and redistribution of air. The Earth’s atmosphere acts as a cohesive unit, connecting all regions and causing us to share the same air. This global circulation plays a crucial role in transporting heat, moisture, and pollutants, influencing weather patterns and sustaining life on our planet. It emphasizes the interdependence of all living beings, and reminds us that we’re in this together.