Atmosphere

1. Atmosphere

2. Unit Overview • Redistribution of energy by atmospheric and oceanic circulation • Global Heat Budget • Causes and impacts of the Intertropical Convergence Zone

3. Air Pressure Basics High Pressure = Air is cold = sinking. Low Pressure = Air is warm = rising.

4. Equator v Poles Equator Poles Cold heat means that air is sinking = High Pressure Energy Deficit • Strong heat means that air is forced up = Low Pressure • Energy Surplus

5. The End Goal – for energy to be even throughout the world! The Big Question How does planet Earth manage to redistribute energy throughout the world? (How do we get the spare energy from the Equator to make up the deficit in the Poles?)

7. Diagram Time!!!

9. THE THREE CELLS TOGETHER Polar Cell Ferrel Cell Hadley Cell Hadley Cell Ferrel Cell Q Polar Cell

10. The Winds!!!!

11. Key Points • Surface Winds always blow from high pressure to low pressure. • Coriolis Effect (due to earths rotation) causes winds to be deflected: • Winds in Northern Hemisphere = to the right. • Winds in Southern Hemisphere = to the left.

12. ASSOCIATED SURFACE WIND PATTERNS Winds always blow from high pressure to low pressure (top to bottom) They are deflected because of the Coriolis Force which come about because of the rotation of the earth. Polar high pressure Mid latitude low pressure Sub-tropical high pressure Winds in Northern Hemisphere are deflected to the right. Equatorial low pressure Winds in the southern hemisphere are deflected to the left. Sub-tropical high pressure These wind belts shift seasonally. Mid latitude low pressure Polar high pressure

13. Air Pressure by Latitude

14. Task: Own Diagram • Can you now make your own neat, colourful version of what you have just learnt – can be 3D. • Include: • Three Cells = Hadley, Ferrel, Polar – make hot and cold air clear. • Surface Winds (direction).

15. Atmospheric Energy Redistribution – FROM MEMORY!

16. Exam Question • Explain how atmospheric circulation cells and surface winds redistribute energy throughout the world (6).

17. Explain atmospheric circulation (6) • The equator receives more insolation from the sun because the Earth is fatter and closer to the sun here. • The equator has an energy surplus, while the poles have energy deficit. Atmospheric circulation works to fix this and takes energy polewards. Hadley • Air is heated at the equator and rises with low pressure, this air then spreads out high in the atmosphere. • When the air reaches the tropics (33ON) it sinks (as it has cooled down) at the high pressure zone. • Surface winds then return the air back to the equator but are deflected to the left because of the Earth’s spinning (coriolis effect) Polar • At the North Pole (90ON) dense cold air sinks and starts the Polar cell • Surface air is (again) defected due to Earth’s rotation but always travels from areas of high to low pressure • When air reaches 66ON it hits low pressure and rises up into the atmosphere, here it spreads and loops round into the Polar cell. Ferrel • The Ferrel cell takes energy between Hadely and the Polar cell but is thermally indirect (not affected by differences in heat) and only works to complete the cycle. These cell movements are mirrored in the southern hemisphere.

18. How does the oceans distribute energy round the globe?

19. Overview • Like atmospheric circulation, ocean currents help to redistribute energy across the earth. • Because they cover 71% of the earth's surface, the oceans receive 71% of the sun's energy that reaches earth. • The ocean holds on to this heat for longer than the land does and the ocean currents move this heat around, from the tropics to higher latitudes. In total, ocean currents transfer about 25% of the global heat budget. • You get warm ocean currents and cold ocean currents.

21. Simplified Diagram • Gulf Stream • North Atlantic Drift • Labrador • Canaries

22. Gyres • Currents set up roughly circular shaped loops called gyres.

24. Answering an exam question... • Explain how the oceans help to maintain the global energy balance (up to 10). • Evaluate how effective the oceans are at balancing energy on Earth (up to 10).

25. How do the distribute energy? • Sun hits the equator at 90o meaning concentrated rays. • Oceans store this insolation and can transfer it. Water expands when heated and is pushed north and south. • Cold dense polar water sinks (labrador currents), then spreads towards the equator where it pushes up the less dense warmer water which moves off towards the polar areas.

26. The coriolis effect means the ocean currents are sent in a clockwise direction in the northern hemisphere and anti clockwise in the southern hemipshere. • Pattern is only seen in large oceans that are not interrupted by land masses (which can deflect and block movement of currents) – Equatorial current is deflected due to south America continent. • Surface winds help push ocean currents along (trade winds drive the pattern between 0 and 30 degrees north and south and the westerlies create the pattern between 30 and 60 degrees north and south).

27. UK • Relatively mild, wet winters due to the effect of the North Atlantic Drift – extension of the Gulf Steam

28. El Nino • Periodic change in the currents • Equatorial current which moves west across the Pacific, fails to do so. • Winds die and a large pool of warm water in the Pacific moves east – can cause storms, fish to die etc.

29. Answering an exam question... • Explain how the oceans help to maintain the global energy balance (5). • Evaluate how effective the oceans are at balancing energy on Earth (5).

30. Model Answer – Ocean Redistributing Energy The Earths ocean currents are effective in redistributing energy from areas of surplus to areas of deficit (Equator to Poles). Insolation at the equator can penetrate into the oceans (1 MARK) where it can be stored and transferred. Transfer happens in a clockwise motion in the northern hemisphere as a loop or gyre. Water is heated at the equator and travels as the Gulf Stream. This links onto the North Atlantic Drift which takes the warm water towards the UK (1 MARK). The water cools in the north and sinks deep with the oceans to begin its journey back to the Equator (labrador currents) (1 MARK). The cold currents travel underneath the warm currents to complete loop and join the equator again (canaries) (1 MARK). A similar loop in an anti clock wise direction distributes the energy from the equator to the south pole (1 MARK). This is deflected by land masses and the coriolis effect (1 MARK).

31. Mixed Question – Atmosphere and Ocean… • Explain how energy is redistributed throughout the globe through both the atmosphere and the oceans (10).