Aquatic Science Fall Final Review 2015-16

Tides The rhythmic/periodic rise and fall of the ocean’s water High tide = rising, incoming tide, flow Low tide = receding, outgoing tide, ebb Tides are very long, slow waves

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

Types of Tides Spring Tide Moon and sun are in direct line with one another Results in unusually high tidal range 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

Waves A complex mix of water and energy. Mostly caused by winds (i.e. surface waves) -Also earthquakes, volcanoes, gravitational pull

Wave Characteristics Parts of a Wave Crest = high point Trough = low point Height = vertical distance from crest to trough Wavelength = Horizontal distance between crest to crest or trough to trough

Tsunami vs Surface Waves Out on the open ocean, Tsunami waves are: Fast (hundreds of mph) Not tall (up to 3 ft) Out on the open ocean, surface waves are: Relatively slow (5-65 mph) Much taller than tsunami waves (up to 45 feet)

Coriolis Effect The apparent deflection of the path of air, due to the rotation of the earth

Upwelling Cold, nutrient-rich water rises to replace the surface water (good for fishing- Peru) process is dominant when winds are parallel to coastline

Convection + Coriolis cause winds blowing at these angles across the planet “planetary winds” blow constantly

“Westerlies” “Trade winds” brought the Europeans over to the Americas, sent them back to Europe

If the winds are blowing like this, what direction do you predict the ocean surface currents will be moving at the equator?

What direction do north oceans spin What direction do north oceans spin? What direction do south oceans spin? Clockwise or counter clockwise?

This is because they are Basic Wind-Driven Currents

Two types of Currents: Surface Currents: These waters make up about 10% of all the water in the ocean. These waters are the upper 400 meters of the ocean. Deep Water Currents: Thermohaline Currents These waters make up the other 90% of the ocean These waters move around the ocean basins by density driven forces and gravity. The density difference is a function of different temperatures and salinity

Which side of the continent are there warm currents. Cold Which side of the continent are there warm currents? Cold? What direction do each of these currents flow?

Western vs. Eastern boundary vocabulary to know

Western vs. Eastern currents WESTERN BOUNDARY: EASTERN BOUNDARY: HOT and FLOWS TOWARD POLE COLD and FLOWS TOWARD EQUATOR

What is ENSO? ENSO stands for El Nino Southern Oscillation An irregular, periodic climate change caused by variations in sea surface temperatures over the tropical eastern Pacific Ocean On average, occurs every 2-7 years Use of SST anomalies and SOI values to predict these events

Southern Oscillation Index Southern Oscillation Index (SOI) values are calculated using the pressure differences between Tahiti and Darwin. Sustained negative values of the SOI below -8 indicate an El Nino episode. Sustained positive values of the SOI above +8 indicate a La Nina episode.

Normal conditions vs. El Nino Eastern Pacific = colder, cools off with depth much faster Western Pacific = pool of warm water, extending hundreds of meters down El Nino: Warm water extends from the west to the east of the Pacific (across the equator), at the surface and several hundred meters down.

Normal conditions vs. El Nino Weather in Indonesia, Australia, Southwest Asia = wet Weather in CA, Central America, Ecuador, Peru = dry El Nino: Weather in eastern Pacific = warmer, increased rainfall Weather in western Pacific = cool, dry (some drought)

Under El Nino Trade winds and the Equatorial currents are weaker than normal. Warm water builds up in the eastern Pacific. Upwelling decreases in the eastern Pacific because of weakening trade winds. Rainfall increases in the eastern Pacific, and becomes drier in the western Pacific.

ENSO impact on hurricane and severe weather frequency El Nino: Fewer than normal hurricanes More tornadoes and thunderstorms in the southern US La Nina: Higher than normal hurricanes Warm weather for most of US, but drought in southwest

THE END