7. Climate and Climate Change Flashcards
What is albedo
It is the diffuse reflection coefficient, which gives the proportion of radiation reflected to the incident reflection
(high albedo means very reflective)
What are the albedos of clouds
0.4 - 0.9
The earth’s surface has an albedo of 0.1, but its albedo as viewed from space is 0.38, what accounts for this difference
Most of earths features (water, grass, forests, ground) have an albedo between 0.05 and 0.2. The average is brought up by the cloud coverage
When considering a basic atmospheric model what energy sources are there
Solar radiation
Radiation from Earth’s surface
Convection from Earth
Radiation from atmosphere
What are some effects that reinforce global warming
Melting snow and ice (high albedos) will lower the earther albedo
More water vapour in the atmosphere will lead to more backscattering
Increased cloud cover will lead to more backscattering
Higher sea temperatures results in less CO2 being adsorbed, and vegetation dying (more CO2 present)
More CO2 leads to more forests, lower albedo
What are some effects mitigating global warming
Increased temperatures increase algae growth in waters and reduce CO2 concentrations
Adiabatic lapse rate will decrease as a result of increased humidity
What is ocean time delay and how long is it
Due to the oceans’ high thermal inertia, a change in temperature in the atmosphere will take time to register in the water temperature
50-100 years
What leads to variations in solar radiation flux
Sun spot fluctuations (accounts for 1% flux variation)
Eccentricity of 3% in earths orbit
What factors make the oceans a crucial part in the thermalhydraulics of the planet
- Cover 71% of Earth’s surface
- Just the first 3.2m depth of the oceans have the same thermal inertia as all of the atmosphere
- Oceans are responsible for half the thermal transport from the equator to the polar regions
How does the temperature vary with height
Troposphere (0-10km) - Decreases with ALR
Stratosphere (10-50km) - Temp. increases with height as short wavelength radiation is absorbed here
Mesosphere (50-90km) - Temp. decreases as density is too low to transfer heat
Thermosphere (90+km) - Temp. increases dramatically due to the presence of energetic solar energy
What would the atmospheric circulation look like if the Earth did not rotate?
Two fields - One side of planet is always hot, and one is cold, hot air would rise on hot side, fall on cold side
What would the atmospheric circulation look like if the Earth rotated slowly?
Four fields - Now acceleration due to rotation forms hadley cells, poles are cold, equator is warm
What does the atmospheric circulation look like with Earth’s (relatively fast) rotation speed?
12 fields - Hadley cells become unstable and split into 3 cogged cells
What are the 3 atmospheric cells?
Hadley cell (warm air rising), Ferrel cell (‘gear’ in middle), Polar cell (warm air rising)
What 3 factors cause differential heating of the Earth’s surface
- Earth’s curvature (energy has further to travel to the poles than at the equator)
- Atmospheric depth (energy has to travel through more atmosphere at poles than at equator
- Albedo variation (higher albedo at poles and deserts)
What are the two jetstreams called
Subtropical (between Hadley and Ferrel) and polar (between Ferrel and Polar)
What effect do the cells and coriolis effect have on wind direction
Air north of the equator will be moving slower (appearing east to west) and flows North to South due to Hadley cell. Hence in the northern hemisphere Hadley cell region the air flows from north east to south west
What dictates regions where heavy rainfall often occurs
Regions where air is carried upwards between the cells become regions of heavy rainfall (tropics) as the water saturation decreases with altitude (and therefore temperature)
What dictates regions where deserts often occur
Where cold air at high altitudes sinks it warms up and becomes dry. These are where deserts form
What is the salt content of sea water
3.2-3.8% (lower salt concentrations near equator, higher at mid latitudes)
What is the thermocline
layer of water 10-100m deep that has a steep temperature gradient. Below this layer, the temperature is almost isothermal
What are the 3 layers of the ocean
Mixed (0-10m)
Thermocline (10-100m)
Deep or Abyssal (100m+)
What causes ocean currents (global conveyer belt)
Sea ice (pure water) forms at poles
This increases the concentration of salt
Concentrated brine is more dense and sinks (downwelling)
Brine fills the ocean floor
Returns to the surface at lower latitudes (upwelling)
Draw and label the temperature variation with height of the earths atmosphere
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90km——-‘——————————————————
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50km—————————’———————————
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10km———–’—————————————————
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…………………………………………………..’……..Troposphere.
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State three mechanisms which can attenuate the solar radiative flux passing through the atmosphere.
Molecular scattering (Rayleigh) Particulate scattering (Mei) Absorption
Sketch the vertical temperature and salinity profiles
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Explain why some environmentalists and climatologists are worried about the potential consequences of global warming on the thermohaline circulation
Climate change may result in a change of the ocean flow patterns and this in turn can result in dramatic localised shifts in weather patterns (e.g. the gulf stream enjoyed by the UK may disappear and result in a significant drop in UK temperatures even though global warming results in an overall (global) increase in temperature)
Also, increasing the melt rate of ice and reducing the generation rate will cause increases in sea level and flooding in some parts of the world
What is thermohaline circulation?
Thermohaline circulation thermo (temperature) and haline (salt) mismatches gives rise to buoyancy forces which in turn result in flows/circulation
List some reasons why salt concentration in the ocean varies
- evaporation (more at poles) increases concentration
- precipitation (more at equator) dilutes concentration
- ice formation at poles increases local concentration
- rivers/estuaries bring pure water into sea
