Moon’s Motions

Part 1. Moon Phases

A. Luminous1. Produces its own light (Sun, stars)

B. Illuminated1. Seen by reflected light (moon, planets)

C. Moon Phases1. Apparent changes in the shape of the

moon (different parts are illuminated by the Sun)

2. Moon Lit Up

Part 1. Moon Phases

D. Waxing1. Moon “growing” in size2. Light on RIGHT side

E. Waning1. Moon “shrinking”2. Light on LEFT side

F. Synodic Month1. Time to complete the moon phase

cycle2. 29.5 days

Part 2. EclipsesA. Solar Eclipse

1. Eclipse of sun

2. Occurs ONLY during NEW moon

Part 2. EclipsesB. Lunar Eclipse

1. Eclipse of moon

2. Occurs ONLY at FULL moon

Part 3. Moon Motions

A. Time for Moon to Revolve = 27.3 days

B. Time for Moon to Rotate = 27.3 days

C. Rotation = Revolution, so same side of moon always faces the Earth

D. Moon Phase Cycle = 29 days (moon must catch up to the Earth)

Part 4. Tides

A. Daily rise and fall of oceans

B. Caused by the pull of gravity of the moon AND the Sun

C. Moon has a greater effect since it is closer to the Earth

Part 4. Tides

D. Spring Tide (nothing to do with season)A. The highest high tide and lowest low tide

occurs

B. Gives the maximum difference between high and low tides

C. Happens during new or full moon

Part 4. Tides

E. Neap TideA. Lowest high tide and highest low tide

B. Gives minimum difference between high and low tides

C. Happens during Quarter moons

Part 4. Tides

F. Time from one HIGH tide to the next HIGH tide is 12 hours and 26 minutes

G. There are about 2 High and 2 Low tides per day

Importance of Waves

• Shaping Coastlines– Erode cliffs– Grind rock into sand

• Ecology– Returns O

2 to water

– Stir up food for filter feeders

Tides• The rhythmic rise and fall

of the ocean’s water

High tide = rising, incoming tide, flowLow tide = receding, outgoing

tide, ebb

Slack tide = vertical movement stops

• Tides are very long, slow waves

– They have a wave period of 12 hours 25 min

– Tidal day is 24 hours 50 min

– NJ has 2 high and 2 low tides daily

1. Gravitational pull of sun & moon on Earth

What Causes Tides?

• Moon closer, therefore > effect

• Like magnet, pulls water away from surface = TIDAL BULGE

2. Centripetal Forces

• Produced by motions of Earth, sun, & moon

• Bulge on opposite side because centr. force > pull of moon

Types of Tides

– 2x’s/month

•Spring Tide - Moon and sun are in direct

line with one another- Results in unusually high

tidal range

-Tidal Range = vertical distance between high & low tides

• Neap Tide– sun and moon are at right

angles

– Pulls cancel each other out – causes a weak pull

– unusually low tidal range

– 2 x’s / month

Spring vs. Neap Tides

Distance bet. Moon & Earth

Perigee Tides• Moon closest to earth, very high tides (causes

flooding)

Apogee Tides• Moon farthest away from earth, very low tides

Types of Tides Continued• Diurnal Tides

– 1 high & 1 low / day– Parts of Gulf of Mexico and Asia

• Semi-Diurnal Tides– 2 high & 2 low / day– Atlantic coasts of North America and Europe

• Mixed– 2 high & 2 low / day (height varies)– Pacific coast

Importance of Tides

• Expose & submerge orgs

• Circulate water in bays & estuaries

• Trigger spawning (grunion, horseshoe crab)

• Circulates food, wastes, etc

Currents• What are currents?

- “Rivers” of circulating water

• Causes- Wind

- Rotating Earth

- Density Changes

Surface Ocean Currents

• Broad, slow drifts; never cross equator

• Wind generated; circular gyres

• Coriolis Effect

- N. Hemis – clockwise; Right

- S. Hemis – counterclockwise; Left

• Gulf Stream

- Brings warm water from equator north along east coast of N. A.

- N. Atlantic

-Sometimes form eddies – circulating water that pinches off from the current

MIGRATION NAVIGATION

WEATHER

Localized Surface Currents

Longshore Current.

– Flows parallel to shore; move sediment

RIP CURRENT

- Caused by converging longshore currents

- Very dangerous ; Red Flag

- DO NOT fight rip current; swim parallel to shore to get out of channel

Deep Ocean Currents

• Separated from surface currents by boundary called a “Thermohaline” (diff in densities)

Flow beneath surface; cross Flow beneath surface; cross equatorequator

Move North to SouthMove North to South

Importance Of Deep Currents– Upwelling

• Brings deep water to surf.• Circulates nutrients up• Moves plankton & larvae