3 What is wind?The movement of air in a horizontal direction
4 What causes wind?The uneven heating of the Earth causes differences in air pressure.
5 Why does this happen?The Sun’s energy is more concentrated at the Equator and spread out more over the poles.Air over the equator is warm and less dense and has lower pressure.Air over the poles is cold and denser and has higher pressure.
6 Why does this happen?As warm air at the equator rises, cooler air from the poles will move in and replace it.Air pressure moves in a pattern from high to low.
7 ConvectionAs warm air at the equator rises, cooler air from the poles will move in and replace it.
8 Global Convection Currents The density changes caused by temperature changes create convection cells.These cause circular patterns of air that circulate over the whole planet.
9 Global Wind BeltsWhere the convections cells meet, prevailing winds and jet streams form.They blow from one direction over a certain area of the Earth’s surface.
11 Jet StreamForms high in the upper Troposphere between two air masses of different temperaturesHigher temperature difference = faster speedDue to the Coriolis Effect, it flows around air masses.Polar Jet:It dips southward when frigid polar air masses move south.It tends to stay north in the summer months.
13 Prevailing Winds Named for the direction from which they blow: Polar Easterlies – High latitudes blow east to west toward the equatorWesterlies – Mid latitudes blow west to east toward the polesEasterlies (Trade Winds) – Low latitudes blow east to west toward the Equator
15 Prevailing WindsPressure belts form in between the wind belts.
16 MoreDirect Sun Hot 0 o Equator 30 o S 60 o S 90 o S 30 o N 60 o N
17 Global Wind Belts The winds from the poles blow toward the equator. The winds from the equator blow toward the poles.
18 If wind is moving north and south, … …then why is it defined as the horizontal movement of air? *Reflection Question* Does the Earth stand still?
19 The Coriolis EffectAs the Earth rotates counterclockwise, the winds bend and curve around the Earth.Gustave-Gaspard Coriolis, an engineer and mathematician, described this effect as an inertial force in 1835.
20 The Coriolis EffectIn the Northern Hemisphere, winds bend to the right of their direction of travel.In the Southern Hemisphere, winds bend to the left of their direction of travel.Let’s try a little investigation to see how this works.
21 The Coriolis EffectWeather patterns and systems move in a circular motion due to the bending of the winds caused by the Earth’s rotation.
22 Equilibrium Our Earth is always seeking balance. In an effort to find balance, there is a continuous cycle of patterns.Reflection Question* What is the driving force behind the changes that create these patterns?
29 WindJust as wind moves from high pressure to low pressure areas, so does the water.Winds blow across the surface of the water, causing friction.The water piles up because the surface currents flow slower than the winds.
31 GravityAs water piles up and flows from high pressure to low pressure, gravity will pull down on the water.This forms vertical columns or mounds of water.The Coriolis Effect causes the water to curve.
32 The Coriolis EffectCauses water to move to the right in the Northern HemisphereCauses water to move to the left in the Southern Hemisphere
36 GyresVertical columns or mounds of water at the surface and flow around themProduce enormous circular currentsFive major locations:North Pacific - clockwiseSouth Pacific - counterclockwiseIndian Ocean - counterclockwiseSouth Atlantic - counterclockwiseNorth Atlantic - clockwise
41 The Great Ocean Conveyor: Helps maintain Earth’s Balance
42 Deep Water Currents Make up about 90% of oceans’ water Differences in density cause them to move.Differences in density are related to temperature and salinity.At high latitudes, they sink deep into the ocean basins.Temperatures are so cold, they cause the density to increase.
43 Reflective QuestionHow are ocean currents produced?
44 El NinoAbnormally high surface ocean temperatures off the coast of South AmericaCauses unusual weather patterns acrossthe globe
45 El NinoStarts because the easterly trade winds weaken and allow the warm waters in the Western Pacific to move east toward South AmericaThis changes where the convection current occurs.Causing rain where it usually doesn't occur and drought where it usually rains
48 La NinaAbnormally low surface ocean temperatures off the coast of South AmericaCauses unusual weather patterns acrossthe globe
49 Ocean’s Effect on Climate Ocean currents move more slowly than winds.Oceans hold more heat than the atmosphere and land.Cold currents will cause nearby coastlines to be cooler.Warm currents will cause nearby coastlines to be warmer.Where do the cold currents come from? The warm currents?
50 Predictable Patterns How do these currents affect the climate of the coastline?
51 Reflection QuestionsHow do our oceans impact climate?