Why weather systems are apt to stall. A new theory tries to explain enigmatic "blocks" that bring heat waves and drought
Voosen, Paul
Few weather phenomena are as widely experienced, but poorly understood, as an atmospheric block. When a block arises, typically at the western edge of a continent, the jet stream splits, wrapping around a blob of seemingly static air thousands of kilometers across and pinning it in place. Such blocks can last for weeks, and drive heat waves, drought, and winter cold snaps. Yet atmospheric scientists have struggled to understand why blocks occur and last so long, and how they might change in a warming world. Spurred by a debate over a connection between Arctic warming and midlatitude weather, several scientists have returned to the fundamentals of theories of blocking to offer new answers. </p>
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