Lecture 6: Global Energy Movement Flashcards
Where is there an absorbed solar energy surplus/deficit on the planet?
Near the poles, more energy is emitted as infrared radiation than is absorbed by solar radiation, but at the equator, more energy is absorbed than is emitted.
At +/- 35˚ lattitute, the net energy deficit/surplus is zero.
T or F: Solar radiation is equally distributed across the globe.
F: solar radiation is concentrated at the equator.
This is because sun rays hit the equator perpendicularly (more concentrated), where sun rays hit the poles at an angle (due to the earth curvature) and a larger surface area absorbs the same amount of light (less concentrated).
If above 35˚ lattitude there is a net energy deficit, why are the poles not continuously getting colder?
Heat is transferred from the equator to colder regions through atmospheric and oceanic circulation.
What are the forms of atmospheric energy circulation?
pressure-driven air movement
landform-driven air movement
rotation-driven air movement
water vapour transport
What are the forms of oceanic circulation?
Surface ocean currents
Deep ocean currents
How does pressure-driven air movement work?
Uneven solar heating causes temperature contrasts between air parcels. This difference in temperature compresses/expands the air parcels, creating a pressure gradient between the parcels. This pressure gradients causes air to flow from high to low pressure areas, transporting the heat with it.
This is how wind is formed!
How does landform-driven air movement work?
Warmer/denser air near the sea level can be forced higher into the atmosphere by high relief landforms (such as mountains). The higher parcels have less atmospheric pressure exerted on them, causing them to expand and cool down (why mountains can have snow on them). As the air parcels move past the high relief areas and back down to sea level, there is more pressure exerted on them, causing them to contract and heat up.
How does rotation-driven air movement work?
Since the planet rotates, movements which would usually be straight actually curve with the rotation of the planet (aka the Coriolis effect).
How does water vapour transport effect global temperatures?
Moving between states of matter involved energy changes (latent heat). Therefore, if water evaporates at location A, heat is absorbed in that region. The wind moved the cloud of water vapour to location B, where it condenses, releasing that energy.
What drives atmospheric air/water vapour circulation?
Global differences in heat surpluses/deficits
What are the three main circulation cells?
Hadley Cell
Ferrel Cell
Polar Cell
Where does the Hadley cell exist?
Begins at the equator and descends at 30˚ north and south
Where does the polar cell exist?
Begins at 60˚ north and south and descends at the poles
Where does the ferrel cell exist?
Rises at 60˚ and falls at 30˚
What drives the ferrel cell?
Being sandwiched between the two bigger cells: polar and hadley
This makes the ferrel weaker and more variable, and it also goes in the opposite direction as the other two.
