Global Warming Exam 1

Climate (traditionally)

30 year mean of weather

Climate subsystems (contemporary)

1. atmosphere

2. ocean

3. cryosphere (snow/ice)

4. biosphere

5. lithosphere (land)

Black Body

theoretical object that absorbs all incident radiation and reradiates that energy (stefan boltzmann)

Planck Curve

• Power Density = rate energy is emitted per m² per unit wavelength per unit (Planck Function)

• Cooler T = longer wavelength

Kirchoffs Law

good absorber = good emitter

Radiative Equilibrium

energy absorbed from the sun = energy emitted by the Earth

Solar Constant (S0)

rate solar E is incident on a unit area perpendicular to a solar beam

Earths Current = 1361 W/m²

Solar Luminosity (Ls)

total energy output of the sun

Observed global and annual average surface temp

288K or ~58 *F

Why is the solar constant NOT constant

1. peaks 11 years apart (sunspot cycles) → ~2 W/m² change

2. changes due to earths orbit every 10-100’s of years

3. Solar evolution mill to bill years

Rayleigh Scattering

• small particles < 0.1 nano meter diameter

• scatters blue light (shorter wavelength)

• why the sky is blue

Mie Scattering

• larger particles in the atm. (dust, smoke, water droplets)

• no preferred wavelength

• why clouds are white and smoke is grey

radiance

amount of energy being observed at the top of the atmosphere

How closely do observed solar/terrestrial spectral match Planck curves

for solar → very similar

for terrestrial → big dips (CO2)

Green House Gasses

absorb long wave radiation emitted by the surface and reemitted that radiation in all direction @ their own temp

Molecular absorption/reemission

changes direction and wavelength of radiation (green house effect)

Short wave effects of clouds

reflects → cool the climate system

Longwave effects of Clouds

absorb → warm the climate system

3 types of heat exchanged

1. radiation (LW,SW)

2. Sensible Heat

3. Latent Heat

Fback

the infrared energy emitted by greenhouse gases, clouds, and aerosols in the atmosphere back down toward the Earth's surface

Incoming Heat in the Energy Balance

F back, S abs (absorbed solar rad)

Outgoing Heat in the Energy Balance

Black Body Emissions, Latent Heat, Sensible Heat

Sensible Heat

the rate heat is transferred from the atm to the ground by conduction

Latent Heat

Energy absorbed or released by water during phase changes (evaporation, condensation, freezing, melting) at constant temperature.