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Meteorology
3.3.5.7 Variation of air pressure with height ................................................. 231
3.3.6 Altimeter ...............................................................................................232
3.3.6.1 Altimeters ......................................................................................... 232
3.3.6.2 Transition layers, transition altitude and transition level ................... 235
3.3.6.3 QNH, QFF, QFE, QNE ......................................................................... 236
3.3.6.4 Pressure altitude and density altitude .............................................. 238
3.3.6.5 Air density and flight performance ................................................... 245
3.3.6.6 Venturi effect ................................................................................... 245
3.4 Pressure and wind .................................................................................. 246
3.4.1 High pressure and low pressure ............................................................ 246
3.4.1.1 The globale wind system and high-pressure and low-pressure belts . 247
3.4.2 Atmospheric movement ....................................................................... 248
3.4.2.1 Pressure Gradient Force ................................................................... 248
3.4.2.2 Coriolis Force ................................................................................... 249
3.4.2.3 The Polar Front................................................................................. 250
3.4.2.4 The Jet Stream ................................................................................. 251
3.4.2.5 The independence of high- and low-pressure systems ...................... 251
3.4.3 The Earth’s surface and the geostrophic wind ....................................... 253
3.4.3.1 The geotrophic wind......................................................................... 253
3.4.3.2 Surface wind .................................................................................... 254
3.4.3.3 Pressure Gradient Force ................................................................... 255
3.4.4 Local winds ........................................................................................... 257
3.4.4.1 Sea breeze ........................................................................................ 257
3.4.4.2 Land breeze ...................................................................................... 257
3.4.4.3 The Föhn wind .................................................................................. 258
3.4.4.4 Rotor winds in the mountains........................................................... 258
3.4.4.5 Valley winds and mountain winds..................................................... 259
3.4.5 Mechanical and og thermal turbulence ................................................. 260
3.4.5.1 Mechanical turbulence ..................................................................... 260
3.4.5.2 Thermal turbulence .......................................................................... 260
3.4.6 CB’s and gust fronts .............................................................................. 260
3.4.7 Microburst ............................................................................................ 262
3.4.8 Wind in relation to flying ...................................................................... 262
3.4.8.1 Wind speed and wind direction - given in METAR ............................. 263
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© marts 2026 208
