Air mass antarctic barometric pressure chinook closed low continental air mass diffraction dust bowl fetch fogbow hygrograph instrument flight rules (ifr) mist positive vorticity advection pre-frontal squall line ridge snow blindness stagnation area subtropical air summer undercast unstable/ instability. Absorption bow echo chemosphere condensation funnel diffluence downdraft evapotranspiration eye eye wall filling fresh water fusion gustnado heat stroke hydrologic cycle hygrograph isohel isopleth palouser