lecture 4 Flashcards
what is climate driven by?
Climate is ultimately driven by incoming and outgoing solar radiation (earth’s energy budget)
what does the atmosphere determine?
- What hits the earth is determined by the atmosphere
○ Nitrogen
○ Oxygen
○ Argon
Co2
what do aerosols change
Aerosols change the long term pattern of atmosphere and climate
sea level vs atmosphere spectrum of solar radiations
- Holes in the sea level graph are from components of the atmosphere
Ozone is the balance between uv radiation hitting atmospheric oxygen
why is the atmosphere system balanced?
- Average energy budget of the earth-atmosphere system
- Why must the earth attempt at maintaining a balance
That atmospheric layer without balance would cause big shifts in temperature
- Why must the earth attempt at maintaining a balance
how much of incoming solar energy is scattered?
30% relfected back to space (backscatter)
clouds 16%
air, dust, haze, 6%
earth’s surface 7%
how much solar radiation is absorbed by atmosphere
~23% absorbed by atmosphere
absorbed by h2o, dust, o3
absorbed by clouds
how much solar energy reaches earth? how much is used in photosynth?
~50%
<1%
is earth in a state of radiative balance?
As a global long term average, earth is close to a state of radiative balance
how is SR balanced?
amount incoming (shortwave) = amount outgoing (short and long wave)
true for each layer: above atmosphere, atmosphere, earth’s surface
what is convection
Convection: heat transfer by turbulent movement of air or water, divided into: Latent heat reflux:
Sensible heat flux:
describe latent heat refux
○ Latent heat reflux: energy transferred between a surface and the atmosphere by the evaporation of water or the condensation of water vapor (phase change)
describe sensible heat flux
Sensible heat flux: energy conducted from a warm surface to the air immediately above it, and moved upward to the atmopshere (no phase change)
NGHE?
- Natural greenhouse effect
- Warming of atmosphere due to atmospheric absorption (by radiatively active gases) of longwave radiation
Maintains earth at 15 degrees C; without NGHE, earth would be around 33 degrees C cooler
- Warming of atmosphere due to atmospheric absorption (by radiatively active gases) of longwave radiation
Radiatively active gases
- Absorb and reradiate long wave radiation emitted by earth
- H2O, CO2, CH4, N2O, O3, CFCs
- Mean Residence times (mrt)? what is it for n2, o2, and co2
- Total mass divided by the flux into or out of the atmosphere over a given time period
- N2 has a MRT ~13 million years
- O2 MRT 10,000 years
- CO2 MRT = ~5 yrs (50% decline in 30 years with ceasing of emissions, 70% decline within a few centuries)
Spatial variation in climate is due to?
- Due to:
○ Atmospheric system - composition and circulation
○ Oceans and ocean circulation
○ Landform effects (topography, albedo)
look at atmosphere structure diagram
ok
describe troposphere
- Troposphere (the weather layer)
○ Ends ~10-16 km
○ Temp declines with height
○ Heated from below; absorbs LW radiation emitted from earth
Tropopause
describe stratosphere
○ Above troposphere (to ~48 km)
○ Temp increases with height
○ Heated from above (SW solar)
○ Uv protector; contains O3 which absorbs UV radiation
* Record is 12km deep
* Bacteria found about 6km deep
* Layers marked by temperature changes
○ Zig zag temp change
* Why are there these changes in atmospheric temp?
Interaction of gases and incoming radiation
what is the planetary boundary layer? why is it important? daily rhythm?
- The surface of air that is attached to the planet
- Daily rhythm
○ The cloud layer moves up throughout the course of the day -As the day warms up - Important in how we interact with the air we breathe
- Smog, pollution is important in this boundary layer
- If its low we will be breathing in more
- Daily rhythm
what does atmospheric circulation cause
Fundamental cause= uneven heating of the earth surface
causes of uneven heating?
- Spherical shape and tilt of earth’s axis
- Sphere
○ Equator receives more radiation than poles
1. Shorter atmospheric path
2. Concentrated in smaller area
○ Greater temperatures at equator
○ Drives heat movement (atmospheric circulation) from equator to poles - Global seasons
○ Spherical shape and tilt of earth’s axis leads to uneven surface heating
○ Drives changes in seasons in N and S hemispheres
○ Tropics: seasonal variation in temp and day length are slight, but precipitation may vary greatly
*
- Sphere
solar driven air circulation patterns?
- Uneven heating drives air circulation patterns and conequently precipitation patterns
As the air goes up its less dense
how does air circulate?
Sun heats air at equator & warm air rises
Air cools-condenses -rain -tropics
Now dry air moves N/S (cooling &
becoming dense) & sinks at 30degrees lat.
Dry air draws moisture from the land -deserts
Air continuing N & S completes thermal
loop (Hadley cell)
3 atmospheric cells?
on either side of equator
polar cell
ferrel cell
hadley cell
look at diagram
