The polar jet stream guides weather systems. When it meanders, Rossby waves develop. Large-amplitude waves stall into blocking patterns that persist for weeks.
Fast, straight flow. Weather systems move rapidly eastward. No persistent patterns.
• Quick-moving storms
• Normal temperature patterns
• Regular precipitation cycles
• 5–7 day weather predictability
Rossby Wave Dispersion: Phase speed c = U − β/k² (Rossby 1939). Waves propagate westward relative to the mean flow. Long waves (small k) move faster westward. Stationary waves: U = β/k². Arctic amplification (reduced Arctic-equator temperature gradient) may increase wave amplitude, causing more frequent blocking — a topic of active research (Francis & Vavrus 2012 hypothesis, debated).