Hydrosphere 1 session 2 Flashcards
What are the 2 main drivers of ocean currents?
wind or gravity
What are the 2 main types of ocean currents?
surface
thermohaline
What are surface currents driven by?
winds
What ocean volume is affected by wind/ surface currents?
10% by volume only upper ocean
What is ocean stratification?
the layering of the ocean due to density (usually temp but can be salinity)
What is the surface zone of the ocean?
2% volume well mixed by waves and currents
What is the pycnocline?
18% volume layer of rapidly changing density
What is the deep ocean zone?
stable 80% volume
Why is water good at storing heat?
due to high het capacity
Why are ocean climate relatively mild?
ocean absorbs heat in summer and releases heat in winter
What are the 3 ways of heat transfer?
conduction
convection
radiation
What is conduction?
molecular agitation without motion of the material as a whole (heat diffusion)
What is convection?
by mass motion in a fluid (gas or liquid)
What is radiation?
by particles (photons) or waves through empty space
What is the Coriolis effect?
controlled by how earth spins on axis
NH to the right
SH to the left
What is a geostrophic gyre?
oceanwide circular current bounded by the continents, westerly winds, and the trade winds
What is gyre circulation like?
clock-wise in the northern hemisphere and counter clock-wise in southern hemisphere
What causes gyres?
wind friction
Coriolis effect
How do wind friction and the Coriolis effect currents below the surface?
NH Coriolis deflects wind to right
Next layer down does not feel the wind,
but the movement of the water above exerts a force
What is the average movement for the whole water column in the NH?
90* to right of wind direction
What is the net motion of fluid (90* to wind) called?
Ekman transport
What creates gyres?
water piles up NH due to right movement of water
Pressure gradient created
Gravity pulls some water back down slope
What are geostrophic gyres a balance between?
as direction 45* balance between Coriolis effect and pressure gradient
What causes upwelling in NH?
wind comes from north
water moved offshore by Ekman transport
Water has to rise to fill water moved out (downwelling opposite wind south water pushed out as surface water goes closer to coast?
