Moon’s Motions

Part 1. Moon Phases Luminous Illuminated Moon Phases Produces its own light (Sun, stars) Illuminated Seen by reflected light (moon, planets) Moon Phases Apparent changes in the shape of the moon (different parts are illuminated by the Sun) Moon Lit Up

Part 1. Moon Phases Waxing Waning Synodic Month Moon “growing” in size Light on RIGHT side Waning Moon “shrinking” Light on LEFT side Synodic Month Time to complete the moon phase cycle 29.5 days

Part 2. Eclipses Solar Eclipse Eclipse of sun Occurs ONLY during NEW moon

Part 2. Eclipses Lunar Eclipse Eclipse of moon Occurs ONLY at FULL moon

Part 3. Moon Motions Time for Moon to Revolve = 27.3 days Time for Moon to Rotate = 27.3 days Rotation = Revolution, so same side of moon always faces the Earth Moon Phase Cycle = 29 days (moon must catch up to the Earth)

Part 4. Tides Daily rise and fall of oceans Caused by the pull of gravity of the moon AND the Sun Moon has a greater effect since it is closer to the Earth

Part 4. Tides Spring Tide (nothing to do with season) The highest high tide and lowest low tide occurs Gives the maximum difference between high and low tides Happens during new or full moon

Part 4. Tides Neap Tide Lowest high tide and highest low tide Gives minimum difference between high and low tides Happens during Quarter moons

Part 4. Tides Time from one HIGH tide to the next HIGH tide is 12 hours and 26 minutes There are about 2 High and 2 Low tides per day

Importance of Waves Shaping Coastlines Ecology Erode cliffs Grind rock into sand Ecology Returns O2 to water Stir up food for filter feeders

Tides The rhythmic rise and fall of the ocean’s water High tide = rising, incoming tide, flow Low 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

What Causes Tides? 1. Gravitational pull of sun & moon on Earth Moon closer, therefore > effect Like magnet, pulls water away from surface = TIDAL BULGE

2. Centripetal Forces Bulge on opposite side because centr. force > pull of moon Produced by motions of Earth, sun, & moon

Types of Tides 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 2x’s/month

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 Circulates food, wastes, etc Trigger spawning (grunion, horseshoe crab)

Currents What are currents? Causes - “Rivers” of circulating water - 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 - N. Atlantic - Brings warm water from equator north along east coast of N. A. Sometimes form eddies – circulating water that pinches off from the current

IMPORTANCE OF SURF. CURRENTS NAVIGATION MIGRATION 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 Flow beneath surface; cross equator Separated from surface currents by boundary called a “Thermohaline” (diff in densities) Move North to South

Importance Of Deep Currents Upwelling Brings deep water to surf. Circulates nutrients up Moves plankton & larvae