Yale professor Ron Smith continues his course The Atmosphere, the Ocean and Environmental Change with a lecture on what drives regional and seasonal climate variation. He covers how latitude shapes precipitation patterns, using annual average precipitation maps, then works through orographic precipitation over mountain terrain and continentality, the difference in how land and ocean surfaces heat and cool, complicated by the uneven distribution of land mass between hemispheres. Ocean currents and biome distribution get their own segments before Smith turns to seasonality itself, explaining how Earth's axial tilt controls the solar insolation reaching the surface over the year and how that shifts climate zones seasonally. Recorded in Fall 2011 as part of Yale's GG 140, the lecture runs through chaptered sections on definitions, latitude, orography, continentality, currents, biomes, and Earth's rotation around the sun, building a systematic account of why climate differs from place to place and season to season.