The Sun Sun is middle aged (4.5 ba / 11 ba) Sun is one of 1011 stars in Milky Way galaxy Sun is big - compare the size of a coronal flare (eruptive prominence) and the size of Earth Radiation produced by fusion of H (75%) to He (24%)
Variability in Solar Radiation Faint Young Sun paradox 2. 11-year sunspot cyclicity
Weather vs. Climate Statistical distribution (climate) of stochastic events (weather)
Water on the Earth’s surface Earth is the “water planet” because H2O can exist in all 3 phases on the surface. Recall water phase diagram. Earth is just the right distance from the sun, to keep water in all three phases. Mean temp. of Earth surface ~= 15oC
Radiation Balance Want to understand the temperature of the Earth’s surface. What is the control volume of interest here? Perform an Energy Flux balance. … and employ the Stefan-Boltzman Law.
Discrepancy: Earth’s predicted vs. observed surface temperature
Blackbody Radiation and Absorption of Certain Energy Wavelengths Atmospheric gasses absorb certain wavelengths of the incoming and outgoing radiation spectra Radiation in the visible (~0.5 micron wavelength) - relatively unaltered The infrared band (~10 micron wavelength) – significant absorbtivity Wein's Law predicts outgoing radiation peaks in infrared band - greenhouse gasses trap outgoing radiation – drives up surface temperatures by about 33K (from -18oC to +15oC)
Distribution of Radiation (Insolation) Snow/Ice-covered poles have very high albedos relative to the oceanic low latitudes.
Poleward Energy Transport Net radiation distribution Continental landmass distribution Oceans and atmosphere (the climate system) transport energy poleward by advection (fluid in motion).
Latitudinal Distribution of Energy Transport The integral of the net radiation balance is the heat transport curve.
Vertical Structure of the Atmosphere Derive pressure and density structure from ideal gas law approximation
Atmospheric Circulation – Hadley Cells
Atmospheric Circulation – Hurricanes