Tides Flashcards
Forced Wave
A wave currently influenced and reliant on forces like wind or gravity
Free Wave
A wave that doesn’t require an external force to stay in motion
What kinds of waves are tides?
Shallow water waves because they have the longest wavelengths and extend all the way to the ocean floor
How many high tides and low tides per day?
2 of each
Why?
The moon causes the high tide bulges and the earth rotates around to each of these points once
Does distance or mass have a greater effect on gravitational pull?
Distance
Why?
Gravitational force is proportional to product of masses
- Greater the mass, greater the gravitational pull
Inversely proportional to square of separation distance
- Increase distance, force greatly decreases
Zenith
The point closest to the moon with the strongest gravitational pull
Nadir
The point farthest from the moon with the weakest gravitational pull
What is the result of gravity and inertia combined?
Centripetal Force
How long is a lunar day?
24 hours, 50 minutes
How long the moon takes to orbit the Earth once
How long is a solar day?
24 hours
Spring tide
The sun and moon align and the forces from the sun and the moon to combine and cause a larger tide than normal
Neap tide
The Sun and Moon form a 90-degree angle with the earth, so their forces cancel out. This results in a lower tidal range and lower tidal level
When does spring tide occur?
Full moon and new moon
When does neap tide occur?
First and third quarter moon
Flood tide
When the water comes toward the shore (High Tide)
Ebb tide
When the water moves away from the shore (Low Tide)
Declination angle
The sun and moon aren’t always directly above the equator (they’re moving in 3D space, so it isn’t exactly easy to occur), so lunar tidal bulges rarely align with the equator
How does the elliptical orbit affect tidal ranges?
The perigee causes greater tidal ranges and the apogee causes lower tidal ranges
Why do tides break into cells?
The rotation of the earth is too strong
Amphidromic point
A point in the ocean where there is little to no tide, crests and troughs rotate around them
Cotidal lines
Lines through areas that have high tide at the same time
(CO means same)
What direction do tidal waves rotate in the Northern and Southern hemisphere
Tide waves rotate counter-clockwise in Northern Hemisphere and clockwise in Southern Hemisphere.
Diurnal tidal pattern
One high and one low in a lunar day (24 hours, 50 minutes)
What is the tidal period for diurnal tidal patterns?
24 hours 50 minutes, a lunar day
Semidiurnal tidal pattern
Two high tides and two low tides each lunar day
What is the tidal period for semidiurnal tidal patterns?
12 hours 25 minutes
high tide is twice as often, so it takes half as long to occur
Mixed tidal pattern
Has characteristics of both, usually 2 high 2 low but not always
Diurnal inequality
When successive high tides and low tides have significantly
different heights
Occurs during a mixed tidal pattern, like having a local and extreme max and min
Most common tidal pattern?
mixed tidal pattern
Mixed tidal pattern period?
Usually 12 hours 25 minutes, but can have a diurnal tidal period
Tidal bore
A wall of water moving toward a narrower low-lying river causing the wave height to increase rapidly (goes sanic fast)
What causes a whirlpool?
Opposing tidal cycles in restricted coastal passageways
What are tide pools?
They occur along coast where ocean meets the land where it’s rocky or has a rapidly changing surface.
Life in them is very varied and has to survive 6-12 hours without protection of water when exposed to high heat. The tidal sequence brings lots of nutrients
