(5) geo: greenhouse effect, earth's energy, etc.

earth receives energy from…

one half at a time

earth emits energy from…

the entire planet

bare rock earth average temperature

-15° C

what accounts for the difference in the earth being -15°C on the bare rock model and the average temperature of +15°C?

the greenhouse effect

greenhouse effect (definition)

longwave EMR emitted by the earth gets re-radiated back to the surface

what do “open windows” do?

they allow for energy to escape

similar to the earth as some longwave EMR’s are trapped while some passes out to space

what causes the greenhouse effect?

vibrating air molecules that make frequencies interact with longwave EMR

what causes the air molecules to vibrate?

temporary dipoles

shortwave EMR from the sun…

transmits through the atmosphere

longwave EMR from the earth…

is absorbed by the atmosphere

are all gases equal?

no, some are better at absorbing longwave EMR than others

according to wein’s law..

earth is not a perfect blackbody due to decreased emission because the atmosphere is absorbing these wavelengths

why worry about CO2 since it’s so weak?

CO2 is very abundant in the atmosphere compared to all other greenhouse gases (other than water vapor)

how is CO2 emitted?

combustion

what is the band saturation effect?

no CO2 in the atmosphere = no absorption

why does the band saturation effect matter?

the earth is very sensitive to small changes in CO2 concentration

no CO2 means

no absorption

CO2 added means

increased absorption and decreased energy

causes the earth to warm and restore imbalance

why is water such an important greenhouse gas?

it absorbs more energy across the greatest wavelength spectrum and responds to climate change

heat

transport of energy by conduction, convection, advection, and radiation

which EMR warms the earth?

shortwave EMR

longwave EMR from the earth is absorbed by…

certain atmospheric gases

what does the greenhouse effect alter?

earth’s energy budget

where does the most of earth’s energy come from?

the equator

where is insolation the greatest?

the deserts

insolation at earth’s surface

high in the tropics, low in the high latitudes

how do deserts receive a lot of energy?

they have low humidity, low water vapor, and not a lot of clouds

thermal equator

the line that connects all of the hottest temperatures on earth at any given point in the year

why is the thermal equator oddly shaped?

insolation patterns

why does the thermal equator shift north and south?

the change in the seasons

isotherms

lines of constant temperature

where is the global temperature range the smallest?

the equatorial region

where do you get the most range?

in the top of the atmosphere

why does it take lots of energy to warm water?

it has a higher heat capacity

why does it take less energy to warm land?

it has a low heat capacity

why are landscapes warmer than their rural or forested counterparts?

albedos and vegetation

more vegetation =

cooler temperatures

less vegetation =

warmer temperatures

urban surfaces, (glass, asphalt, etc.) have…

a lower albedo and increase the amount of energy absorbed

urban structures are tall and can

reduce wind and speed

darker roofs…

absorb more sunlight than lighter roofs and get hotter