7. Climate and Climate Change

Question 1

What is albedo

Answer 1

It is the diffuse reflection coefficient, which gives the proportion of radiation reflected to the incident reflection

(high albedo means very reflective)

Question 2

What are the albedos of clouds

Answer 2

0.4 - 0.9

Question 3

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

Answer 3

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

Question 4

When considering a basic atmospheric model what energy sources are there

Answer 4

Solar radiation
Radiation from Earth’s surface
Convection from Earth
Radiation from atmosphere

Question 5

What are some effects that reinforce global warming

Answer 5

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

Question 6

What are some effects mitigating global warming

Answer 6

Increased temperatures increase algae growth in waters and reduce CO2 concentrations
Adiabatic lapse rate will decrease as a result of increased humidity

Question 7

What is ocean time delay and how long is it

Answer 7

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

Question 8

What leads to variations in solar radiation flux

Answer 8

Sun spot fluctuations (accounts for 1% flux variation)

Eccentricity of 3% in earths orbit

Question 9

What factors make the oceans a crucial part in the thermalhydraulics of the planet

Answer 9

1. Cover 71% of Earth’s surface
2. Just the first 3.2m depth of the oceans have the same thermal inertia as all of the atmosphere
3. Oceans are responsible for half the thermal transport from the equator to the polar regions

Question 10

How does the temperature vary with height

Answer 10

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

Question 11

What would the atmospheric circulation look like if the Earth did not rotate?

Answer 11

Two fields - One side of planet is always hot, and one is cold, hot air would rise on hot side, fall on cold side

Question 12

What would the atmospheric circulation look like if the Earth rotated slowly?

Answer 12

Four fields - Now acceleration due to rotation forms hadley cells, poles are cold, equator is warm

Question 13

What does the atmospheric circulation look like with Earth’s (relatively fast) rotation speed?

Answer 13

12 fields - Hadley cells become unstable and split into 3 cogged cells

Question 14

What are the 3 atmospheric cells?

Answer 14

Hadley cell (warm air rising), Ferrel cell (‘gear’ in middle), Polar cell (warm air rising)

Question 15

What 3 factors cause differential heating of the Earth’s surface

Answer 15

1. Earth’s curvature (energy has further to travel to the poles than at the equator)
2. Atmospheric depth (energy has to travel through more atmosphere at poles than at equator
3. Albedo variation (higher albedo at poles and deserts)

Question 16

What are the two jetstreams called

Answer 16

Subtropical (between Hadley and Ferrel) and polar (between Ferrel and Polar)

Question 17

What effect do the cells and coriolis effect have on wind direction

Answer 17

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

Question 18

What dictates regions where heavy rainfall often occurs

Answer 18

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)

Question 19

What dictates regions where deserts often occur

Answer 19

Where cold air at high altitudes sinks it warms up and becomes dry. These are where deserts form

Question 20

What is the salt content of sea water

Answer 20

3.2-3.8% (lower salt concentrations near equator, higher at mid latitudes)

Question 21

What is the thermocline

Answer 21

layer of water 10-100m deep that has a steep temperature gradient. Below this layer, the temperature is almost isothermal

Question 22

What are the 3 layers of the ocean

Answer 22

Mixed (0-10m)
Thermocline (10-100m)
Deep or Abyssal (100m+)

Question 23

What causes ocean currents (global conveyer belt)

Answer 23

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)

Question 24

Draw and label the temperature variation with height of the earths atmosphere

Answer 24

………………………………………………………………… , ………..’. ………………………………. , …………..’………………………………
…………………….’………………………………………………………..
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…………..’……………………..Thermosphere…………………..
90km——-‘——————————————————
…………………………..’………………………………………………….
…………………………………‘……………..Mesosphere……….
…………………………………….’………………………………………..
50km—————————’———————————
……………………………………..’………………………………………. ………………………………‘……………………………………………….
…………………………..’…………………..Stratosphere……….
……………………‘………………………………………………………….
10km———–’—————————————————
………………………………….’…………………………………………….
…………………………………………………..’……..Troposphere.
…………………………………………………………………….’………….

Question 25

State three mechanisms which can attenuate the solar radiative flux passing through the atmosphere.

Answer 25

Molecular scattering (Rayleigh)
Particulate scattering (Mei)
Absorption

Question 26

Sketch the vertical temperature and salinity profiles

Answer 26

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Question 27

Explain why some environmentalists and climatologists are worried about the potential consequences of global warming on the thermohaline circulation

Answer 27

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

Question 28

What is thermohaline circulation?

Answer 28

Thermohaline circulation thermo (temperature) and haline (salt) mismatches gives rise to buoyancy forces which in turn result in flows/circulation

Question 29

List some reasons why salt concentration in the ocean varies

Answer 29

• 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