quiz on tides/currents

coriolis effect

• caused by the rotation of the earth

• when on a rotating surface, an onject moving on the surface tends to swerve slightly to the left or right rather than continuing ina. straight line

• as wind blows across the ocean in a straight line, the water actually moves in a 45 degree angle from the wind rather than completely with the wind

where does the global conveyer belt start

in the arctic

explain the global conveyer belt

• starts in the arctic, cold water freezes, leaving behind salt. this denser, high salinity water begins a process - downwelling

• this causes a mixing of the water layers until it reaches the bottom

• the water will begin to move south through the atlantic ocean towards Antarctica 

• the belt divides into two sections

• one section goes toward the indian ocean

• this cold water moves northwards towards the equator, bringing nutrients to eastern african coasts. water increases in temp and moves to the surface

• when it cannot rise any higher, it loops back through the south indian ocean as a warm current

what is downwelling

the downward movement of water due tp density differences 

explain the other split of the belt 

• the colder bottom water moves towards the equator to the northern pacific ocean

• water starts to warm and rise, becoming a surface current along west coast of north america

• warm current wraps around Australia and reconnects with the Indian Ocean portion 

last step of the belt

• after the two meet again in the Indian ocean the warm currents move back through the Atlantic ocean back towards the North pole

• this process starts all over again

define spring tide

greatest tidal amplitude

• sun, moon, earth in a straight line

• highest high tide and lowest low tide

• predicted to happen twice a month

• occurs during a full moon and new moon

neap tide 

• smallest tidal amplitude 

• sun and moon are at a right angle

• crescent moons

• highest low tide and lowest high tide

• sun and moon pull in opposite directions causing a smaller tidal bilge 

diurnal tide

1 high and 1 low tide a day

semidiurnal tide

2 high and 2 low tides a day

water around the equator

warm, less dense, less salinity

water around the poles

cold, more dense, more salinity

surface ocean currents

• clockwise spiral in North hemisphere and counterclockwise in southern hemisphere due to coriolis effect

• driven by wind

how to find tidal range

high tide minus the following low tide = tidal range

tidal range