When you picture the deadliest blizzard in human history, you imagine Siberia or Antarctica, not a country associated with arid deserts. Yet the Guinness record belongs to Iran, where a drought-stricken nation was buried under 26 feet of snow in a matter of days.

This episode solves the structural mystery of how a four-year drought collapsed into a localized apocalypse that erased 200 villages and killed at least 4,000 people. We examine the pre-existing vulnerabilities, the meteorological collision that produced the snow, and the desperate, often futile rescue attempts that followed.

• How four years of drought depleted granaries and killed livestock, leaving communities defenseless before the storm hit
• The atmospheric mechanism: polar air absorbing moisture from the Caspian Sea and Mediterranean, then dumping it via orogr ...