Chapter 12

Earth energy imbalance

- Energy balance is never quit perfect: the distribution of incoming solar energy is always changing due to season, or with longer term of ice-age cycle that alter earth's albedo. - energy imbalance results largely from increased greenhouse gas concentration

what is greenhouse effect? and how does it work? be able to name three greenhouse gases?

- greenhouse effects are those infrared gases in Earth's atmosphere. - greenhouse gases inhabit outgoing infrared radiation, making it difficult for earth to shed energy it gains from the sun. -Three greenhouse gases are CO2, Methane (CH4), Nitrous oxide (N2O), -the greater greenhouse gas is H2O not CO2

Energy Balance

- if the rate of energy flowing into an object is equal to the rate of energy flowing out, then the object stays at constant temperature. -heat losses depends on the temperature difference between the outside and inside. - transferring energy energy from hotter place to colder place in order to have a balanced energy.

Figure 12.5 ( interaction between Earth's surface and atmosphere)

-341W/m2 is the incoming solar radiation from averaging the direct 1,364W/m2 above earth's atmosphere over the full surface area of our sperical planet. -30%-some 102W/m2 of the incoming solar radiation is that's refelcted back into space without being absorbed by the earth or it's atmosphere. -most of the reflection- 79 W/m2 is from clouds and reflective particles in the atmosphere.another 23W/m2 reflects from the surface, much of it from ice and desert sand. -The fraction that is reflected from the sunlight is called albedo, it's major determinant of climate. - Take away reflected 102W/M2 from the 341W/m2 of incident sunlight and you're left with 239W/m2 as the rate at which the earth atmosphere system actually absorbs solar energy. -the total incoming radiation is about equal to the total outgoing radiation, 341-239-102=0 because the earth is very close to being in thermal equilibrium. -evapotranspiration- moves energy from the surface to the atmosphere in the form of the latent heat of water vapor. - Together, convention,radiation and evapotranspiration from earth's surface carry total 493W/m2 into the atmosphere. is flowing downward from both sunlight 161W/m2 + infrared from the atmosphere 332W/m2 = 493W/m2 so the surface energy is balance. atmosphere absorbs 78W/m2 sunlight energy, 17W/m2 coming from surface by convection, 80W/m2 evapotramspiration.

Radiation And Atmosphere

-Earth's atmosphere is largely transplant to visible light. -clouds and other anthropogenic origin reduce visible lights.

A tale of Three planets

-The 3 planets Venus, Earth and Mars corroborate the theory of the greenhouse effect. Mars has a tenuous atmosphere and very little effect; earth's atmosphere contains enough greenhouse gases to increase its temperature by 33oC; and venus has runaway greenhouse gases effect of some 500oC.

Is the Earth in energy balance right now?

-the planet reaches energy balance, its temperature remains constant unless the energy input varies. -planet's energy loss occurs by radiation only. -To reach energy balance, the loss rate must equal the rate of energy input. -the dominate energy source is sun. -so the earth energy isn't balance.

Green House effects

1-An insulting blanket- the extra insulation reduces the outgoing energy flow, energy loss rate-until new energy balance established at higher temperature. 2-Infrared, Up and down- surface- emitted infrared escapes directly to space, since greenhouse - free atmosphere is transparent to infrared as well as to visible light. -less infrared going out so the plant is no longer in energy balance. - As the greenhouse gases gases absorbs infrared, they warm up and share their energy with surrounding atmosphere. 3- Warm below, cool above-