Rossby Waves

Tropopause variation with latitude

Jet stream – wind field and temperatures

Isotachs and isotherms

Mid-latitude Cyclones Formation revisited

Polar front

Upper atmosphere pressure and winds

Current circulation model

Tropical Climate

Monsoon

Asian monsoon - 1 Winter (northern hemisphere) Cold air over Asia creates high pressure. Dry air drawn southwards from Himalaya

Asian monsoon - 2 Summer (northern hemisphere) Land heats to give low pressure over Asia. Moist air drawn northwards from equatorial oceans

Hurricane Mitch

Distribution of Hurricanes

Hurricane Damage Scale Number Category Central Pressure mb inches Wind Speeds mi/hr knots Storm Surge feet meters Observed Damage 1>=980 >= ~1.5 some damage to trees, shrubbery, and unanchored mobile homes ~ major damage to mobile homes; damage buildings' roofs, and blow trees down ~ destroy mobile homes; blow down large trees; damage small buildings ~ completely destroy mobile homes; lower floors of structures near shore are susceptible to flooding 5<"920" <"27.17" >"155" >"135" >"18" >"5.5" extensive damage to homes and industrial buildings; blow away small buildings; lower floors of structures within 500 meters of shore and less than 4.5 m (15 ft) above sea level are damaged

Hurricane Eye Wall

Cross-section of hurricane

Spin up process Air converges from radius of order 1000 km Air that is stationary w.r.t. the earth is travelling eastwards w.r.t. a frame of reference fixed in space at a speed Hence air drawn from N travels more slowly and that from S faster than the centre of the hurricane, leading to rotation. convergence rising air, condensation release of latent heat surface low pressure R θ Ω relative to space Conserving angular momentum about eye mvr is constant so: relative to earth