The Atmospheric Circulation System Geos 110 Lectures: Earth System Science Chapter 4: Kump et al 3 rd ed. Dr. Tark Hamilton, Camosun College

Overall the Earth’s Climate is in Balance In Balance Kind-of: But you have to average over night and day It helps to average for many seasons or years And we need to overlook trivialities like burning all of Earth’s fossil Carbon from the past ~350 Ma in < 3 centuries! However: Region to region there are hot and cold spots, wet and dry places, rain forests and deserts, mountains and plains, seas and glaciers, tropics and polar climes & a whole lot of weather!

There are Big Latitudinal Differences The Tropics have Energy Surplus The Poles run a Deficit Temperate zones have transitory seasonal swings

There are Big Latitudinal Differences IR emission doesn’t match? How does heat move? The Tropics have Energy Surplus The Poles run a Deficit Temperate zones have transitory seasonal swings

There has to be a Global Circulation System IR conversion to Latent Heat (Water  Vapor) Convection driven by density and pressure differences between different air masses

Weather & Climate Vary Across the Globe Wind & Ocean Currents Redistribute Solar Heating Solid Earth processes buffer CO 2 levels by weathering rocks Eddies on all spatial & temporal scales prevent the redistribution from being complete or even.

Eastern Pacific & Central America w/ ITCZ Intertropical Convergence Zone NOAA Satellite Image Cloud Band marks ITCZ at top of Troposphere The Troposphere, heated from below convects

Convective Towers Cumulonimbus drive Hadley Cells of ITCZ Cloud Band marks ITCZ at top of Troposphere Solar Evaporation & Latent Heat from Condensation make the heat pump that drives the Convection

Horizontal & Vertical Air Movements result from Temperature & Pressure differences driving Buoyancy Buoyancy is due to density contrasts, Δmass/volume Fast molecules, more collisions more F/A = Pressure Temperature increase  Pressure increase Pressure increase  Volume increase, buoyancy Air columns heated from below expand and rise Other denser air moves in laterally to replace it Cooling upper Troposphere cools air shrinks & sinks