Wind and waves Flashcards
In what latitudinal regions is there more solar energy being reflected back into the atmosphere?
the polar regions
What is the term for the reflection of solar energy back into the atmosphere?
albedo effect
How is wind created?
- air over land warms and rises (low pressure)
- air cools as it moves away from land, descends
- cool air moves towards land (high pressure)
What are the circulation cells on Earth called and where are they found?
hadley cells = 0* (equator) towards 30* (tropics)
ferrel cells = 60* (subtropics) towards 30* (tropics)
polar cells = 60* (subtropics) towads 90* (poles)
Define the Coriolis effect
- the deflection of moving particles (i.e wind/waves) as a result of the Earth’s rotation
- strongest towards the equator due to the faster rotation
- reflects to the right in the NH and to the left in the SH
Which winds are found between the equator (doldrums/convergence zone) and the horse latitudes (subtropics)?
easterlies/trade winds (blow to the left)
Which winds are found between the horse latitudes (subtropics) and polar fronts (subpolar)?
westerlies (blow to the right)
Which winds are found between the polar fronts (subpolar) and the poles?
polar easterlines (blow to the left)
What percentage of wind is transferred as surface currents?
2% (only top 100-200m of water)
In what directions do gyres circulate in the different hemispheres?
NH = clockwise
SH = counterclockwise
What are the main gyres?
North pacific, south pacific, north atlantic, south atlantic, indian
What causes upwellings?
- surface winds and the coriolis effect cause ekman transports that push warm water away from coasts
- colder, nutrient rich water from below the surface rises to replace the warm water
What are downwellings?
movement of oxygen rich water from the surface into the depths as a result of wind currents moving water towards the shore (Ekman)
How does density-driven mixing work in each season?
summer = warm, light water forms top layer, cold dense water sinks to bottom, both separated by thermocline layer
fall = surface water cools due to air and sinks, upwells deeper water towards the surface
winter = density evens at all depths, wind currents forcefully push surface water deeper
spring = surface water warms due to air, establishes a thermocline layer against denser cooler water below
What are some of the water masses?
- North atlantic central surface water (NACSW)
- Mediterranean intermediate water (MIW)
- North atlantic deep water (NADW)
- Antarctic intermediate water (AAIW)
- Anarctic bottom water (AABW)
In what two areas do deep water formations occur and what happens?
- Greenland and Weddell Sea
- cold dense water sinks and drives thermohaline circulation (temp + saline driven)
What does the oceanic conveyer belt accomplish?
- distributes heat globally
- delivers oxygen to deep water
- upwells nutrients to shallow water
What is the relationship between a wavelength and a wave base?
1/2 of the wavelength = wave base
What are the restoring forces behind capillary and gravity waves?
capillary waves (wavelength < 1.7cm) = surface tension
gravity waves (wavelength >1.7 cm) = gravity
What do the ratings 0, 3, 8, 10 and 12 mean on the Beaufort scale?
0 = calm
3 = light breeze
8 = gale, strong winds
10 = storm
12 = hurricane, max gale
What is the difference between spilling and plunging breaker waves?
spilling = calm transfer of energy, gradual dissipation
plunging = sudden transfer of energy, wave curls over itself as it crashes
What is a spring tide?
the highest tides caused by the full moon, new moon and sun aligning with the Earth and causing the maximum horizontal pull
What is a neap tide?
the lowest tides caused when the 1st/3rd quarter moons are 90 degrees to the sun, causing the weakest horizontal pull
What is the difference between diurnal and semidiurnal tide cycles?
diurnal = one max tide, one min tide a day
semidiurnal = 2 max tides, 2 min tides a day
What are amphidromic points/tidal nodes?
areas where the difference in high and low tides is negligible
