Chapter 9: Tides

Question 1

What are tides?

Answer 1

periodic raising and lowering of ocean sea level.

Question 2

What are the main causes of tides?

Answer 2

tides are caused by the gravitational attraction of the sun, moon, and earth.

Question 3

What is gravity? What two factors determine gravitational force?

Answer 3

A natural phenomenon by which physical bodies attract each other with a force proportional to their mass.

Question 4

What two factors result in the two tidal bulges? Where are the two tidal bulges?

Answer 4

the sun and the moon. one toward the moon and one toward the sun.

Question 5

How long is a lunar day? Why is it longer than 24 hours?

Answer 5

24 hours and 50 min. Its longer because the moon revolves around the earthin the same direction as earth so it takes an extra 50 min.

Question 6

Define flood tide and ebb tide.

Answer 6

flood tide- water moves toward shore

ebb tide-water moves away from sun

Question 7

What causes the monthly tidal cycle?

Answer 7

the month long phases of the moon.

Question 8

When do spring and neap tides occur? Which has the greatest tidal range?

Answer 8

Spring tides- occur during new or full moons and have the least tidal range.
Neap tides- occur during quarter moons. has the greatest tidal range.

Question 9

What is declination and what effect does it have on tides?

Answer 9

declination is the angular distance of the moon or sun above or below the earths equator.

Question 10

Define perihelion and aphelion and state the time of year that each occurs.

Answer 10

perihelion-(january) greatest tidal range here

aphelion-(july) tidal range least here

Question 11

Define perigee and apogee. When is the tidal range the greatest?

Answer 11

perigee-(moon closest to earth)-tidal range greatest.
apogee(moon furthest from earth)tidal range least.
perigee-apogee cycle 27.5 days

Question 12

What are some factors that prevent the tidal bulges from actually forming?

Answer 12

The continents are the big reason, but others include friction w/ seafloor, and tides cannot keep up with earths rotation

Question 13

Describe diurnal, semidiurnal and mixed tidal cycles. Draw a graph of each.

Answer 13

Diurnal- one high and one low tide per day
semidiurnal- 2 highs and 2 lows per day(tidal range about the same)
Mixed- 2highs/2lows per day(tidal range differs) most common

Question 14

What place has the world’s largest tidal range?

Answer 14

The bay of fundy nova scotia, CA

Question 15

What is a tidal bore?

Answer 15

wall of water that moves up certain rivers and is tide generated

Question 16

Define flood current and ebb current. When do high slack water and low slack water occur?

Answer 16

flood current-produced when water rushes into a bay or river with an incoming high tide.
ebb current- when water drains out of a bay or river because low tide is approaching.
high slack water-(occurs at the peak of each high tide)
Low slack water-(the peak of low tides occurs)

Question 17

why does the moon control the tides more tha the sun

Answer 17

because the moon is closer and has the 2x the gravitational pull because of proximity to earth.