Global Atmospheric Circulation and Climate Patterns
Think of Earth's atmosphere like a giant conveyor belt system that moves air around the planet. Winds form because air naturally flows from high pressure areas to low pressure areas, creating predictable patterns that drive our weather.
The atmosphere works through three circulation cells in each hemisphere: Hadley, Ferrel, and Polar cells. Here's how it works: the Sun heats air at the equator, making it rise and create low pressure. This warm air cools as it moves away from the equator, then sinks at 30° north and south, forming high pressure belts where you'll find many of the world's deserts.
Trade winds blow from these 30° zones back toward the equator, whilst westerlies blow from 30° toward the poles. Understanding this system helps explain why certain regions have consistent weather patterns and why storms move in predictable directions.
Climate has always changed naturally. During the Quaternary period (the last 2.6 million years), Earth cycled between cold glacial periods lasting 100,000 years and warmer interglacial periods lasting 8,000-12,000 years. However, in just the last 200 years, temperatures have risen 0.8°C - that's incredibly fast in geological terms.
Key Point: The greenhouse effect occurs when greenhouse gases absorb long-wave radiation reflected from Earth's surface and re-radiate it back, trapping heat in our atmosphere.