Earth's life support systems Flashcards
What is the saturated adiabatic lapse rate (SALR)? Why does it cool at a slower rate than the dry adiabatic lapse rate (DALR)?
SALR is the rate at which a saturated parcel of air cools as it rises into the atmosphere. It cools at a rate of about 7C per kilometre because it lets out latent heat as it cools. DALR cools at a rate of about 10C per kilometre.
How does orographic uplift cause precipitation?
If the relief of the land is hilly or mountainous, air is forced to rise above the obstruction of the landscape. The rising air cools at a faster rate, creating instability in the atmosphere. Clouds form due to this instability.
Sequestration
The take-up and long-term storage of carbon dioxide.
Evaluate the importance of the physical pump in sequestering CO2 into the oceans.
The physical pump has great importance as not only does it sequester carbon by diffusion, but it also mixes it throughout the oceans via downwelling and upwelling, creating a more even distribution. Downwelling assists in the long-term storage of carbon at ocean depths. Upwelling brings cold, carbon- and nutrient-rich waters to the service, on which phytoplankton thrive, therefore assisting the biological pump. Carbon diffuses back to the atmosphere, linking the fast and slow carbon cycles.
Carbon capture and storage (CCS)
CO2 is separated from fossil-fulled power station emissions. It is compressed and transported. It is then injected into porous rock underground and stored.
Explain how forestry affects the dynamic equilibrium of the carbon cycle.
Increasing the number of trees increases carbon stores in both the trees and the soil. As the trees grow, they take in more carbon, promoting further growth and creating positive feedback. However, forest trees are an effective carbon sink for about 100 years. This is why sometimes they are then felled and reforestation is repeated. This creates a negative feedback loop, as carbon is released during felling.
Net primary productivity (NPP)
Energy produced by plants, taking into account energy used for respiration.
Assess short-term changes impact on the water cycle.
- Short-term changes occur daily (diurnally) or seasonally. Diurnal changes are significant to flows as less evaporation and transpiration at night and no convectional precipitation. Seasonal changes vary depending on global location. In summer months there is typically more flow evapotranspiration than precipitation. River flows reduce in summer months. There are reduced stores of water in the soil. Short-term changes are more significant to local and regional water cycles.
Assess long-term changes impact on the water cycle.
Long-term changes involve glacials and interglacials and are significant on a global scale. During glacials, water is transferred from the ocean water store to a store of ice on land. Glacials reduce the flow of water considerably as there are much lower rates of evapotranspiration.
Why is increased water vapour in the atmosphere considered such a danger?
It creates an important positive feedback loop: a warm atmosphere = more evaporation and more water vapour in the atmosphere = more absorption of thermal energy radiated from the Earth = a warmer atmosphere, and so on. Water vapour controls the Earth’s temperature and accounts for a high proportion of the warming effect.
How does sea surface temperature affect the sequestration of CO2?
Warmer SST means the ocean’s ability to absorb CO2 decreases. Therefore more CO2 is left in the atmosphere, which causes the problem to continue (positive feedback).
