Lec 6. Global Energy Movement Flashcards
how is solar radiation distributed across the globe
It is concentrated at the equator, but it stretches near the “top” North and “bottom” South, the area absorbing the energy is greater at the poles
how does solar radiation distribution impact the global energy?
- it creates energy surpluses and deficits.
At the poles; Energy emitted as IR radiation is greater than solar radiation being absorbed.
At what latitude is there an energy deficit (negative net radiation) ?
above 35° lattitude !
why are areas above the 35° latitude not cooling down if they have an energy deficit?
It has to do with the global systems that are in place; that transfer surplus heat from the equator to the colder regions at the higher lattitudes
What are the 2 main systems that move the energy surplus ?
Atmospheric circulation
Oceanic circulation
What are the 4 types of movement that are part of the atmospheric circulation?
- pressure-driven air movement
- landform-driven air movement
- rotation driven air-movement
- water vapor transport
What are the 2 currents found in the oceanic circulation?
- Surface ocean currents
- Deep ocean currents
what is air pressure?
the weight of molecules pressing down on each other in the atmosphere
How does air move when it is under high pressure?
it gets pulled towards the areas with lower pressure
what is the relation between temperature, air, density and pressure
Pressure = Density x (constant) x Temperature
what is an air parcel?
an area of air that is of a different temperature or pressure than the surrounding air
What is the initial cause of pressure-driven air movement?
the uneven distribution of solar radiations on the planet
why is there snow on top of mountains even in the equator?
Because of landform-driven air movement, Higher reliefs of landforms force parcels of air higher into the atmosphere,
As air is forced upwards:
- Decrease in pressure, molecules in. the air expand, they lose energy, air becomes colder
How does the rotation of the planet affect air movement?
Mouvement which would normally be straight actually curves with the rotation of the planet (the Coriolis effect)
Do they release or take in energy?
1. Evaporation
2. Condensation
- takes in
- releases
when is condensation common in the atmosphere?
- air temperatures decrease
- where air rises and expands
what are common scenarios where condensation happens?
- circulation cells where warm and humid air rises, and as a result expands and cools
- on the side of a high landform as an air parcel is pushed vertically upwards and cools
- at night, as air temperatures decrease in response to the loss of incoming solar radiation
what are the 3 main circulation cells
- Hadley Cell
- Ferrel Cell
- Polar Cell
What is the Polar cell?
It starts at 60° north and south and ends up falling at the polar regions
much colder but enough of an energy different to drive a circulation cell
What is the Hadley Cell?
It is the big circulation cell
starts at the equator
goes 30° north and south
relatively free of water vapor
What is the Ferrel Cell?
- rises at 60° and falls at 30°
- moves in the opposite direction of the Hadley and Polar
- driven by the movement of the Hadley and the Polar
- weaker and more variable
what are surface winds?
- global pattern of movement of air in the atmosphere
- driven by circulation cells and the rotation of the planet (Coriolis effect)
what are surface currents driven by?
surface winds
what do landforms do to currents?
they can trap or deflect currents
what are the differences that drive deep ocean circulation?
it is driven by differences in water density (impacted by temperature and salinity)
what is the cause of ocean salinity?
minerals weathered from land and both evaporation and ice formation in the ocean
what is the major driver behind deep ocean circulation?
cold polar regions
- colder water (dense)
- greater salinity (driven by ice formation)
why does adding salt to roads delay ice formation?
because as ice forms, salts and minerals need to be left behind
how does ice formation lead to greater salinity levels?
The water left behind by ice formation has a higher salinity because when ice forms, salts and minerals are left behind
what is the thermohaline circulation?
it is the coming together of the surface currents and the deep ocean currents, forming a global circulation of oceanic currents
salt temperature driven circulation
