FW 4421 Week 8

Svante Arrhenius

First person to imagine humans could change the climate of the earth; first imagined it would take 1000 years or fossil fuels to change the climate, changed that as usage changed

Joseph Fourier

Hypothesised Earth’s atmosphere kept it warm

John Tyndall/ Eunice Newton Foot

Demostrated CO2 and water vapor could trap heat

Blackbody

Opaque and non reflected; at room temperature, it looks black because no photos from the visible wavelengths are emitted

Wien’s displacement law

Peak in wavelength of the emissions spectrum is directly related to an objects temperature

Stefan Boltzmann Equation

Power divided by area approximates temperature to the fourth

First law of themodynamics

Energy is conserved; If something is loosing energy then something else is gaining energy, and vice versa

Albedo

Reflectivity of a surface

Assumption one of the one layer model

The atmosphere is transparent to visible light

Assumption two of the one layer model

The atmosphere is opaque to infrared photons emitted by Earth’s surface

Assumption three of the one layer model

The atmosphere acts as a blackbody emitting photons equally to Earth and space

What is adding layers in a model equivalent to?

Adding more CO2 to the atmosphere

Solar constant

1370 watts per square metre

Average energy Earth receives from the sun

268 W/m2

α

Albedo

Estimated α on Earth

0.3

Estimated proportion of energy absorbed

1-α=1-0.3=0.7

Warming magnitude of the greenhouse effect

33 degrees celsius

Keeling Curve

First continuous CO2 measurements from Mauna Loa observatory, important to understanding the Carbon cycle on Earth

Keeling curve: overall trajectory

Higher levels of atmospheric CO2

Keeling curve: seasonal variability

Highest in summers (N and S hemispheres), peaks in N hemisphere summer

Ocean Acidification

CO2 dissolves directly into the upper layer of the ocean (as the upper layer is not well mixed in deeper zones), making them more acidic

Missing carbon sink sources

Forests worldwide: Increasing CO2 stimulating photosynthesis, Enhanced nutrient availability, Recovery from past disturbances, Greater high-latitude productivity

Troposphere

Where we live, avg height of 12 km, higher in the tropics (15 km) because of greater radiation and convection

Weather: influences

Happens in the troposphere, stratospheric winds 12-50 km) influence it

Sensible Heat

Occurs by conduction or convection, what we feel as changes in air temperature

Latent heat

When energy is absorbed or released during phase changes of water

Net radiation distribution

25% maintains a sensible heat flux from the surface to the atmosphere while 75% is latent heat used to evaporate water

Hadley Cells

Tropics, thermally direct; cause belts of desert/semi-arid forests at 20-40 degrees North and South because of descending dry air

Ferrel Cells

Mid-latitudes, thermally indirect

Polar Cells

Polar latitudes, thermally direct

Conduction

Molecule to molecule, slow

Convection

Spatial movements of fluid due to turbulence (fast), dominant mechanism of heat transfer in the atmosphere

Latitudenal heat imbalance

Poles are warmer due to convection, eg hurricanes; Ocean circulation transfers heat

Gulf stream

Carries warm water to the North Atlantic region, makes Europe much warmer than it otherwise should be