Upwelling and El Niño Flashcards
(42 cards)
What drives our climate?
- Short wave radiation from the sun
- Latitude
- Tilt of the Earths axis (seasons)
What balances the energy received from the sun?
Outgoing radiation
A balanced climate is reached when incoming and outgoing radiation are equal
What is outgoing radiation dependent on?
Temperature
Will incoming and outgoing radiation be equal on all places on Earth?
- No!
- Tropics (hot) will emit more long wave radiation than the poles (cold)
What forms atmospheric circulation cells?
Hot air rising and cold air falling
What are Hadley Cell?
- Warm air rises from the equator
- Cool air sinks 30º and splits in two directions
1. Towards the equator (this completes the Hadley Cell)
2. North (poleward)
What are Ferrel Cell?
Cold northern air from Hadley cells encounters air moving southward from the poles
Air moving North from Hadley Cells = key driver in the formation of Ferrel Cells
What are Polar Cells?
- Cold air sinks and moves outward from the poles towards lower latitudes
- Cold air meets warm air moving poleward from Ferrel Cells
- The meeting point is the polar front (60º)
- The polar front causes warm air to rise over cold air
- Warm air will eventually cool and sink back down completing the circulation
What forms Hadley, Ferrel and Polar cells?
- Direct solar heating forms Hadley and Polar Cells
- Ferrel Cells exist due to movement of air between Hadley and Polar Cells
What is the importance of Hadley, Ferrel, and Polar Cells?
All three cell structures combined form major trade winds
(ex: the Easterlies which are important for what?)
What is an Ekman Spiral?
The process by which wind interacts with the ocean to form upwelling
What drives the formation of Ekman spirals?
The Coriolis effect
Water = deflected to the RIGHT in the NORTH and to the LEFT in the SOUTH
What is Ekman Transport?
The NET movement of water
How is water deflected in the northern hemisphere due to Ekman transport?
90º to the right
How is water deflected in the southern hemisphere due to Ekman transport?
90º to the left
What is required for the formation of an Ekman Spiral?
Steady sustained wind
What is Ekamn Transport doing?
Moving water offshore
How is Ekman transport key to upwelling?
- Conservation of mass!
- Prevailing winds + Ekman Transport move enough water off shore
- Water must be replaced due to conservation of mass BUT if you are next to a land mass there is no more water to pull from
- So…water must come from depth
- Water that surfaces is cold and high in nutrients
How can you tell which hemisphere you are in based on upwelling currents?
- Water pulled from the left = southern hemisphere
- Water pulled from the right = northern hemisphere
What causes downwelling?
Water piling up on the coast leads to sinking
What are the 5 major coastal currents associated with upwelling areas?
- Canary Current
- Benguela Current
- California Current
- Humboldt Current
- Somali Current
What is the thermal dome?
Unique feature in the Pacific Ocean where trade winds and marine currents result in upwelling of cold nutrient-rich water from the deep
Describe equatorial upwelling
- Trade winds move surface water from east to west
- Due to the Coriolis effect water is deflected on either side of the equator (RIGHt in north/LEFT in south)
- Surface water moving away from the equator creates a gap that is filled by deep water from below
How does upwelling affect primary productivity?
It increases
