# Water and Wind Unit Chapter 13 Sections 2 & 3 Pages 380-388.

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Water and Wind Unit Chapter 13 Sections 2 & 3 Pages 380-388

Section 2 Ocean Currents & Climate I CAN state how wind & Earth’s rotation influence surface currents Ocean water never stands still, it is always moving

Convection- The process where either warm water/air will rise & cool/cold water/air will sink creating a circular motion or current ◦ Cooler water/air is more dense than warm water/air therefore heavier; that is what causes it to sink  Cool currents sink back to the equator ◦ The sinking cool water/air forces up the warmer water/air which is less dense Question: What might be cooling down the water enough to make it sink?

Current- the flow or movement of either water or air due to the direction of the wind and Earth’s rotation ◦ Similar to rivers that flow at different levels of the ocean or atmosphere ◦ Exists is both the surface of the ocean and in deep water as well as the air (wind) Question: Have you ever swam in a large body of water and felt a current that you could not see? Question: Is the wind a current?

Wind- A flow or current of directionally moving air ◦ Due to the Earth’s counterclockwise rotation, the Northern Hemispheres wind patterns typically blow from the west to the east ◦ Can be either a warm or cold wind pattern ◦ Ocean current mimic wind patterns

◦ Current direction is due to Earth’s rotation, ocean currents DO NOT flow in straight lines ◦ In the Northern Hemisphere current flow to the right ◦ In the Southern Hemisphere currents flow to the left

I CAN explain how ocean currents affect weather & climate Surface currents- an ocean current that is powered by the wind that usually moves only the upper few hundred meters of water in the oceans ◦ Example: The Gulf Stream is a broad, slow, warm current that starts near the equator ◦ Currents on eastern coastlines are usually warm & currents on western coastlines are usually cold

Climate ◦ If a warm current flows past a body of land, the current’s warm water will heat the land giving it a warm, mild climate ◦ If a cold current flows past a body of land, the current’s cold water will cool the land giving it a cool, wet, foggy climate Question: Why would the eastern coastlines have the warm currents? (Think about rotation.)

I CAN describe the causes & effects of density currents ◦ Winds do not affect water that is deeper than a few hundred meters Density Current- a current that forms when more dense seawater sinks below less dense sea water ◦ Seawater becomes more dense as it gets colder or becomes more salty

Cold, dense ocean currents flow along the ocean floor back toward the equator If these currents were to stop flowing, it would result in dramatic climate shifts which include the change of rainfall and temperature patterns Question: Density current are very similar to What other vocabulary word?

Upwelling- a current in the ocean that brings deep, cool water to the ocean surface ◦ Occurs along coasts where winds blowing parallel to the coast cause surface water to move away from the land ◦ Nutrient rich water that many ocean organisms live in ◦ Can affect climate similar to cold ocean currents

El Nino event happens every few years where the warm winds blowing up from Peru lessen which allows the west coast to warm up and stops upwelling in that area Creates a warm moist environment for the spring and summer months in the United States

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