Final review Marine Science

Explain the term semi-diurnal tide.

Two high-tides and two low tide each day

Identify one possible reason for the slight variation in the times of the tides over the two days

The variation in tide times is influenced by the gravitational pulls The variation in tide times is influenced by the gravitational pulls of the Moon and the Sun
and their relative positions to Earth, which change slightly each day.

State two environment factors that influence tides

• Wind

• Air pressure

Describe and explain how the alignment of the Sun, Moon and Earth could impact the tidal
range

When the Sun, Moon and Earth are in a straight line, a spring tide forms
• this causes the greatest tidal range
• Because the alignment amplifies the gravitational effect of the Moon and Sun on the Earth.
• When the Sun and the Moon are at a right angle to each other and the Earth, a neap tide form
• This causes the smallest tidal range
• Because the gravitational pull of the Moon is counteracted by the gravitational pull of the Sun

Explain how a low pressure system would impact the tidal range at Ft. Lauderdale

• During low-pressure systems, seawater swells

• Causes a greater tidal range than normal.

Describe the normal atmospheric conditions characteristic to this location during non-El
Nino years

• Winds blow the water away from the coast of South America towards Australia;
  • That keeps the air over the Australia moist
  • Air above Peru is dry

Describe the characteristic atmospheric changes observed during an El Niño event.

Prevailing trade winds reduce their speed, or inverse, blowing from west to east
• This brings moisture over the South America, causing heavy rain in Peru;
• Australia suffers from draught conditions

El Nino impacts the upwelling in the southern Pacific Ocean. Describe what upwelling is and
how is it important for the fisheries of South Pacific Ocean

Upwelling is the movement of cold, nutrient-rich water from the bottom of the ocean to
the ocean’s surface.
• This acts as a fertilizer, increasing the productivity of primary producers
• An increase in biomass of producers, causes an increase in the biomass of consumers
• Increasing the fish stocks of the region.

Compare La Nina with El Nino conditions.

La Nina is the opposing phase of El Nino.
• Is a cooling phase caused by stronger than normal trade winds
• This allows for more nutrient-rich water to surface the ocean (enhanced upwelling)

Describe the impact La Nina have on local ecosystems

Increase of nutrients in the upper portion of ocean
• Causes an increase in phytoplankton
• And an increase in fish feeding on producers or primary consumers

Explain why volcanoes form at convergent boundary

As oceanic plate slides beneath the continental, regolith melts because of
friction and exposure to high temperature;
• Melted rock is less dense than the surrounding rock and rises;
• Forming volcanoes on the continental plate.