Tides Flashcards
High tides. Where do they form
When part of the pcean is directly facing the moon, the water there bulges toward the moon. At the same time, water on the opposite side of earth bulges because of the rotation of the earth and the motion of the moon around the earth
Low tides
When high tides occur, water is drawb away frim the area between the high tides.
Tide
A daily change in the level of ocean water
Were on the earth. Relative to the moon. Do high tides occur
The part closest to the moon and on the opposite side
How often tides occur and the difference intidal levels depends on what?
The position of yhe moon as it revivles around the earth
The moons pull is the strongest on the earth where?
Its on the strongest in the part of the earth directly facing the moon
What determines when the tides occur?
The rotation of the earth and the moons revolution around the earth
If the earth a d moon rotated at the same speed what would happen?
The tides would not alternate between high and low
What revolves slower the earth or moon?
The moon revolves around the earth much slower then the earth rotates
A spot on the earth that is facibg the moon will take how long to face the moon again?
24 hours and 50 minutes
The sun also affects what?
Tides
Why is the suns influence on tides weaker than the moons influence?
Though the sun is much larger than the moon, then sun is much farther away from the earth
The combined forces of the sub and the moon in the earth results in what?
In tidal ranges that vary based on the positions of all three bodies
Tidal range
The difference between levels of ocean water at high tide and low tide
Declination
As the moon orbits the earth, it’s angle increases and decreases relative to the equator. The tides follow the moons declination and change their angles to match
As the angles of the sun. Moon and earth affect the tidal heights over a lunar month so do what?
Their distances to one another
What is the distance that varies between the earth and the moon- since the moon follows an oval path around the earth
31,000 miles
What happens once a month, when the moon is the closest to the earth (perigee)?
Gravitational/ inertia forces are higher than usual- producing above average tidal ranges
Two weeks later ( after perigee ), the moon is the farthest away (apogee) what happens?
The lunar tide raising force is smaller producing smaller tidal ranges
When the earth is closest to the sun ( perihelion )- occurs about Jan. 2 of each year, what happens?
The tidal waves get larger
When the earth is furthest from the sun ( aphelion ), around July 2, what happens?
The tidal ranges get smaller
If the earth were a perfect sphere without large continents, all areas ob the planet would experience what?
Two equal high and low tides every lunar day
what do the large continents on the planet do?
They block the westerly passage of the tidal bulges as the earth rotates
Most coast. With a few exceptions experience how many a tides a day?
2 both high and low
A lunar day is 50 min longer than what?
A solar day (24 hours)
So lunar day= 1 day + 50 minutes
How long do high tides occur apart from?
12 hours and 50 minutes
Takes 6 hours and 12.5 minutes for the water at shore to fron high to low. Or low to high
The ebb current is greater at low tide. What is greater at high tide?
Flood current
Flood current»» Shore
Tidal current
Horizontal movement of water often accompanies the rising and falling of the tide
Flood current
Incoming tide along the coast and into the bays and estuaries
Outgoing tide
Ebb current
Slack tides
Weakest currents occuring between the flood and ebb currents
Inertia
The tendancy of moving objects to continue moving in a straight line. Acts to counterbalance gravity
Remember this‼️‼️
On the opposite side of the earth, inertia wins out because the moon is farther away so there is a bulgeof water on the side opposite of the moon
Spring tides
Tides with the largest daily tidal range and occur during the new and full moon. Or every 14 days
These occur when the sun. Earth. And moon align
Neap tides
Tides with the smallest daily tidal range and occur during the first and third quarters of the moon
^ occur when the sun. Earth. And moon form a 90 degree angle
After a _____ _____ has been measured, the times that tides occur can be accuratly predicted
Tidal range
In some coastal areas that have narrow inlets, movements of water called _____ _____ occur
Tidal bore
Tidal bore
A body of water that rushes up through a narrow bay, estuary, or river chann l during the rise of high tide and causes a very sudden tidal rise
Tidal bores can occur where? (4 places)
Areas of China. The British Isles. France. Canada
The magnitude of the tides can be influenced by what?
The shape of the shoreline
