The ocean: waves, surface & density currents, El Niño, upwellings & tides

OCEANS 71% of Earth’s surface Affect – –Weather – –Climate – –Food supplies – –Recreation – –Global trade – –Marine life

WAVE transfers ENERGY through space & matter transfers ENERGY through space & matter

WAVES Water molecules move up & down Water molecules move up & down (sitting in a boat and the boat moves up and down) (sitting in a boat and the boat moves up and down) Transfer energy through mediums (water) Transfer energy through mediums (water) Surface movement of a particle of water

wavelength Distance from crest to crest (meters) Distance from crest to crest (meters)

Amplitude Resting position to crest or trough Resting position to crest or trough Measure of the amount of energy Measure of the amount of energy

Wave height Distance from crest to trough Distance from crest to trough Crest to ocean floor Crest to ocean floor

Frequency The # of wavelengths in a certain amount of time The # of wavelengths in a certain amount of time Higher frequency= more energy Higher frequency= more energy

Electromagnetic spectrum

Example of waves Ocean surface waves Ocean surface waves –propagate through water. Radio waves, microwaves, infrared rays, visible light, ultra violet rays, x-rays, and gamma rays (electromagnetic radiation) Radio waves, microwaves, infrared rays, visible light, ultra violet rays, x-rays, and gamma rays (electromagnetic radiation) –Propagation is possible without a medium -vacuum Sound — a mechanical wave Sound — a mechanical wave –propagates through air, liquid or solids (not vacuum) Seismic waves in earthquakes (P, S and L or surface) Seismic waves in earthquakes (P, S and L or surface)

WAVES & SURFACE CURRENTS What we think of as What we think of as Normal ocean waves  driven by wind Normal ocean waves  driven by wind Are the same as Are the same as SURFACE CURRENTS  DRIVEN BY THE WIND SURFACE CURRENTS  DRIVEN BY THE WIND Wind only affects the top ~100m of water Wind only affects the top ~100m of water

What Is a Wave? Most waves form when winds blowing across the water’s surface transmit their energy to the water. Most waves form when winds blowing across the water’s surface transmit their energy to the water.

How Waves Change Near Shore Near shore, wave height increases and wavelength decreases. Near shore, wave height increases and wavelength decreases.

Surface currents

Deep Ocean Currents (Global Conveyor Belt) Driven by density differences in water Driven by density differences in water Density: mass per volume (how compact it is) Density: mass per volume (how compact it is) –Bowling ball and beach ball the same size –Which is denser? –Water: cold and salty = denser

Deep Currents Deep currents are caused by differences in the density of ocean water. Deep currents are caused by differences in the density of ocean water.

Deep Ocean Currents (DENSITY) 1. Surface currents  warm water to poles: 2. warm water cools; cold, denser and salty water sinks Creates a convection current Creates a convection current 3. Deep currents carry cold water to equator 4. Water warms  less dense and rises

Density current FACTS: Deep ocean currents move more slowly than surface currents Deep ocean currents move more slowly than surface currents –Couple cm/second –Surface currents: tens or hundreds of cm/s Takes 1,000 years to complete circuit Takes 1,000 years to complete circuit

Deep Ocean Currents: Why is it important? Brings nutrients to the surface Brings nutrients to the surface helps regulate global temperatures helps regulate global temperatures

Upwelling winds pushes aside surface water by blowing it away and deeper water rises up to replace it winds pushes aside surface water by blowing it away and deeper water rises up to replace it

Effects of Upwelling Brings in nutrients to surface water Brings in nutrients to surface water enables ecosystems to flourish and some in unlikely places (Antarctica) enables ecosystems to flourish and some in unlikely places (Antarctica) Photo courtesy NOAANOAA

El Niño Unusually warm ocean current along the pacific coast of South America Unusually warm ocean current along the pacific coast of South America Caused by weakening in easterly winds Caused by weakening in easterly winds Impact: heavy rains in some areas, droughts in others Impact: heavy rains in some areas, droughts in others

Sea surface temp in

TIDES 2x a day change in ocean level 2x a day change in ocean level CAUSED BY: gravitational pull of the moon and the sun on the Earth CAUSED BY: gravitational pull of the moon and the sun on the Earth MOON MOON

Bay of Fundy

Bay of Fundy, Hopewell Rocks Located between the Canadian provinces of New Brunswick and Nova Scotia, Bay of Fundy features the world's highest, at 16.2 meters, and lowest tides. Located between the Canadian provinces of New Brunswick and Nova Scotia, Bay of Fundy features the world's highest, at 16.2 meters, and lowest tides.

Hopewell high tide

Bay of Fundy- low & high tide

Tsunami A tsunami is usually caused by an earthquake beneath the ocean floor. A tsunami is usually caused by an earthquake beneath the ocean floor.