Meteorology
Blocking events occur when a persistent anticyclone splits or deflects the midlatitude jet stream. Associated with extreme weather: heat waves, cold spells, prolonged precipitation.
c_R = U - β/(k² + l² + λ²)
∂q/∂t + J(ψ,q) = 0
Rossby waves propagate westward relative to the mean flow. A stationary Rossby wave (c_R = 0) can anchor blocking. Rex (1950) blocking index: jet splits into two branches flanking high pressure.