Transcript Slide 1
Higher Atmosphere Earth’s Heat Budget Global Insolation Global Transfer Of Energy Global Temperatures Inter Tropical Convergence Zone Climate Graph 26% Reflected (Albedo) By Clouds 100% Short Wave Solar Energy (Insolation) Limit Of Atmosphere 18% Absorbed By Atmosphere 6% Reflected (Albedo) By Earths Surface (Long Wave) 50% Absorbed By Earths Surface 26% Reflected (Albedo) By Clouds 100% Short Wave Solar Energy (Insolation) Limit Of Atmosphere 18% Absorbed By Atmosphere 6% Reflected (Albedo) By Earths Surface (Long Wave) 50% Absorbed By Earths Surface SOLAR INSOLATION IN EARTHS HEAT BUDGET 100% solar insolation 26% reflected by atmosphere 18% absorbed by atmosphere 56% reaches surface 6% reflected by surface 50% absorbed by surface TOTAL ALBEDO = 26 + 6 = 32% TOTAL ABSORPTION = 18 + 50 = 68% The Heat Budget • Only 50% of the incoming solar radiation (insolation) which reaches the atmosphere from the sun, actually penetrates to the surface of the earth. • Energy which is lost is done so in 2 ways through reflection and through absorption. Earth’s Heat Budget Earth’s Heat Budget Insolation (Task 2) This is incoming solar energy (heat). This is energy or heat emitted from the earth, only 6% escapes the earth the rest being absorbed into the atmosphere. Albedo This is the total amount of energy reflected from the earth. Long Wave Radiation This is the balance between incoming and outcoming energy. The Earth’s Heat Budget To help you, use the following structure. Say where the earths energy come from and name it. Briefly explain what the earth’s heat budget is. Describe what happens to the insolation giving values; •Atmospheric absorption (clouds) •Atmospheric reflection (albedo + clouds) •Surface absorption (land) •Surface reflection (albedo + ice/water) Earth’s Heat Budget (Task 3) The earths energy comes from solarradiation, this incoming heat energy is balanced by the amount of heatescaping back into space. This balance is called the earthsheat budget. Incoming solar heat (insolation) from the sun is absorbed and reflected meaning not all the heat reachesthe earths surface. 26% of the energy isreflected back into space by the earths atmosphereand 18% of the heat isabsorbed by the atmosphere due to dust particlesretaining the heat. This leaves 56% which travels to the earthssurface. Not all of this is absorbed 6% is reflected from the earths surface by polar ice caps& water, and thismakes up part of the earths Albedo. This means only 50%reaches the earths surface and is balanced out by the long wave radiationescaping back into the atmosphere. Variations in Global Temperatures • To understand the reasons as to why the poles are in deficit and the equatorial regions have an energy surplus Global Insolation The Earth's atmosphere is put into motion because of the differential heating of the Earth’s surface by solar insolation. This means that the winds and clouds above us move around because there are some areas of the earth which are hotter than others. We therefore need to know why these difference occur, so we can then study the different movements of the weather in the atmosphere. This then lets us make accurate weather forecasts. Variations in Insolation • The amount of insolation at the Earth’s surface varies according to latitude – most heat is received at the Tropics and least heat is received at the Poles. • As a result, there is a net gain of solar energy in the tropical latitudes and a net loss towards the poles. Reasons for Variations in Insolation • Surface area to be covered is greater at Poles than Tropics so more insolation lost at Poles. • More atmosphere to pass through at Poles than Tropics so more insolation lost at Poles. • Position of sun – the sun is high in sky all year round at Topics whereas at Poles there is no insolation for 6 months of the year. • Albedo. Snow and ice covered Poles reflect insolation. Forested Tropics absorb it. Global Insolation High Albedo Task 4 (1) Different Differing Depths Of Curvature Atmosphere Insolation Low Differing Albedos Albedo Energy From The Sun Global Insolation Task 4 (1) High Albedo Different Curvature Insolation Low Albedo Differing Depths Of Atmosphere Task 5 Latitude & Distribution Of Solar Energy Distance: Insolation from the sun travels different distances, and hence amounts of air, because of the curvature of the earth. At the equator there is a shorter distance to travel, but at the poles there is a greater distance to reach the land. This means that the insolation will be weakened more approaching the poles than at the equator and Curvature: The at curvature of the earth also has an effect on the so make it cooler the poles. distribution of solar energy. The sun’s rays are more concentrated at the equator so it is hotter or has more solar energy. At the poles the same rays are spread over a greater distance so there heat is spread making it cooler. The poles therefore have less solar energy than the Albedo: The high quantities of ice at the poles mean there is a high equatorial regions. albedo (reflection), so that insolation is reflected and the poles receive less solar heat/radiation. The equatorial regions have high concentrations of rainforest, the dark green colour absorbing insolation and so receive more heat. Variations In Global Insolation WithDescribe the aid of an annotated diagram describe Range of latitude and explain the energy shown 35° 35°balance to to 0° 90°N (N or Sonof) ofthe Equ. Equ. diagram below. State Stateififinindeficit deficitororsurplus surplus Givevalues valuesininJoules Joules170 50 to to 270 170 Give Variations In Global Insolation Explain In Detail Why deficit in high latitudes (polar areas) and why surplus in low latitudes (equatorial areas) Insolation - distance travelled through atmosphere greater at poles so heat lost Concentration of insolation higher at equator due to curvature of earth Albedo high at poles and low at equator Global Transfer Of Energy This is the movement of energy from the equator to the poles. Global Insolation differences should mean that the lower latitudes (equator) get hotter and hotter, whilst the higher latitudes (poles) get colder and colder. In reality this doesn’t quite happen as energy is transferred from surplus areas (equator) to deficit areas (poles) by two methods. Atmospheric Circulation & Ocean Currents Atmospheric Circulation (Task 7) Finally the cool air sinks at the poles having distributed heat from the equator to the poles The air warms again and so rises giving rain The cool air then starts to fall back to the earth Hot air at the equator rises This cools as it rises giving cloud and then rain C 90N° 60N° B 30N° A 0° A = Hadley Cell B =inFerrel CellA, B & C. Colour the cells C = Polar Cell Atmospheric Circulation Cells The three weather cells. The Hadley Cell ~ this circulates air between the equator 0° and the tropics of, Capricorn in the south (30°S) & Cancer in the north (30°N). The Polar Cell ~ this circulates air between the North Pole & the Arctic circle (90°N & 60°N) The Ferrel Cell ~ this isn’t actually a cell but circulates air through friction between the tropic of Cancer & Arctic Circle in the North (30°N & 60°N) and the Tropic of Capricorn & Antarctic Circle in the south (30°S & 60°N) Atmospheric Circulation Hadley Cell Equatorial Low Pressure Sub Tropical High Pressure Sub Tropical High Pressure Atmospheric Circulation Polar Cell Cool air falls at the poles. Polar High Pressure 90°N The air spreads south, warmed by the sea and land. As the air rises it starts to cool. 60°N The warm air rises at 60°N. Temperate Low Atmospheric Circulation Ferrel Cell Polar Cell 90N° 30S° Ferrel Hadley Hadley Cell Cell Cell 60N° 30N° 0° Rising warm coolair airair from from Hadley CellCell Air dragged byDescending both Cells causes to Polar circulate, Ferrel Cell, pulls down upthe more air equator with air it. with and distributedrags heat from to it the poles. Atmospheric Circulation Winds The next slide shows how winds move across the surface of the earth. A Key Principle is that these winds move from areas of high pressure to low pressure. Complete the diagram showing surface winds in your workbook. PC 90N° 60N° FC 30N° HC 0° 30S° 60S° 90S° 90N ° Air falling at the Polar High Pressure (90°N) Falling air at move towards thethe 60N Temperate Sub Tropical High Low Pressure ° Pressure (60°N) called(30°N) Polar moves the Fallingtowards air at the Easterlies. Temperate Low Tropical High The Where last air winds rises we 30N Sub (60°S) Pressure (30°N) atreally the Equatorial need to ° called Westerlies. also moves know Low are Pressure called towards the the there South are East light 0° Equatorial Low Trade wind winds called which the Pressure (0°) result Doldrums. from falling called thepressure) North air (high 30S East Trade Winds. at 30°S. ° 60S ° 90S ° Ocean Currents - Global Transfer Of Energy Ocean currents like Cells and wind redistribute energy. Heat is taken from the tropics and moved towards the pole & vice versa. For the exam you will have to describe the movement of these currents and be able to explain why they move in the way that they do. Description of Ocean Currents • Help redistribute energy from areas of surplus to deficit. • Account for 20% of energy redistribution. • Warm currents flow from Equator to Poles. • Cold currents flow from Poles to Equator. • Warm currents – Gulf Stream, North Atlantic Drift. • Cold currents – Canary, Labrador • Move in large circular loops called gyres. • Clockwise in the Northern Hemisphere. • Anticlockwise in the Southern Hemisphere. Factors influencing the flow of Ocean Currents • Winds – currents follow prevailing winds. • Land Masses – block and deflect currents and send them off in other directions. • Corioilis Force - deflects currents to the right in the northern hemisphere and the left in the southern hemisphere. • Salinity(salt) differences in water – flow from low to high salinity – equator – sub-tropics. • Uneven heating of water – cold polar water sinks, flows towards equator and displaces upwards the warmer water setting up gyres. Colour this line red, Colour it this line in blue, it is is the warm Gulfthe cold Labrador current. Stream Colour this line blue, it is the cold Canaries Current Colour this line red it is the warm Equatorial Current Ocean Currents Description These currents form in warm equatorial areas and cold polar areas. In the South the currents flow in an anticlockwis e direction. The currents of the oceans circulate in large loops called gyres. In the North the currents flow in a clockwise direction. Ocean Currents Description In the North Atlantic Gyre a warm A cold current current from from the equator Northern heads Canada, towards calledthe the Labrador Caribbean, current the North joins the Equatorial Gulf Stream Current. coolingIt it then down. moves The current in a North starts Easterly to flow south direction downtowards the African Europe, coast as tothe theGulf equator, Stream theCurrent. Canaries Current, but by now is much cooler. The cycle then starts to repeat itself. Ocean Currents Description The distribution of heat can Theof current thencurrent turns Some the warm actually be seen in a figure of Easterly towards South from the equator, Southin 8 pattern as the two gyres Africa and flows up its Equatorial the AtlanticCurrent, meet atstarts the Western coast, the Benguela to flowRemember South West to the equator. in these Current. current starts BrazilianThe coast, Brazilian questions you to warm up must again asmention it it moves Current, cooling as that warm water spreads up the travels African coast where it South. heat rejoins pole wards the cool the and warm South water helps cool the Equatorial Current. equatorial regions. Ocean Currents Explanation When explaining how these currents circulate there areTask 4 key tosplit make For 14points you will as well as one explaining into groups to find out temperature about these keychnages; points, reporting back to each 1. Wind other what you find. 2. Coriolis effect 3. Position Of Continents 4. Convection Currents 5. You also need to know why the currents warm or cool Ocean Currents Explanation Prevailing Winds Westerlies North East Trade Winds The Trade winds and the Westerlies drive the ocean currents in a clockwise direction a result of falling & rotating air at the sub tropics (30ºN). The equatorial current is picked up by the North East trade winds & sent to the caribbean, the rotation then continues so that the Westerlies send the current to the North East. Ocean Currents Explanation Coriolis Effect This is the West to East rotation of the earth that drives the ocean currents the northern hemisphere in a clockwise direction Ocean Currents Explanation North America Europe The continents deflect currents into a clockwise movement Africa Ocean Currents Explanation More insolation received at the equator than the poles results in convection currents. Warm currents rise at the equator and then drop back down into the sea at higher latitudes, helping to mix warm and cold currents. Ocean Currents Explanation Explaining distribution of cold and warm temperature by currents. You also have to state the obvious! As warm currents move northwards from the equator, they distribute heat to the cooler high latitudes nearer the poles. At the same time, movement of cold currents from the poles to lower latitudes helps to distribute cool temperatures to the warm equatorial areas. Changes In Global Temperatures Diagram Showing Global Temperature Variations 1850 -2000 -0.8 This Trend -0.6 Fluctuates Upwards +0.4 +0.2 1951-1990 Average Global Temperature 0°C -0.2 -0.4 -0.6 1850 1875 1900 1925 1950 1975 2000 Global Mean Temperatures Have Risen Changes In Global Temperatures Diagram Showing Global Temperature Variations 1850 -2000 Highest Value 0.4°C +0.8 +0.6 Temperature Range 0.82 °C +0.4 +0.2 1951-1990 Average Global Temperature 0°C -0.2 -0.4 -0.6 1850 1875 1900 1925 Lowest value -0.42°C 1950 1975 2000 Changes In Global Temperatures Diagram Showing Global Temperature Variations 1850 -2000 -0.8 -0.6 +0.4 +0.2 1951-1990 Average Global Temperature 0°C -0.2 -0.4 -0.6 1850 1875 1900 1925 1950 1975 2000 Rapidly Increasing -0.2 to -0.1°C below Average -0.4 to – 0.3°C Below Average Temperature Above 1920 - 1975 Temperature Temperature 1850 - 1920 Average 1975 - 2000 Changes In Global Temperatures The overall trend is that the Global mean temperature has fallen/stabilised/risen between 1850 & 2000, in a steady/fluctuating manner against the 1951–1990 average/long term average. The lowest value was -0.42/-0.38 °C and the highest +0.4 °C giving a range of -0.2/+0.2/0.78/0.82 °C around the mean for 1950. There was a period with below average temperatures of around -0.4°C to -0.3°C between 1850 & 1920/1850 & 1950/1940 & 2000. There was a period of gentle increase between -0.2°C & -0.1°C below the 1950 average from 1920 & 1940/1920 & 1975. A period of slow/moderate/rapid increase above the 1950 mean took place between 1940 & 2000/1975 & 2000. Changes In Global Temperatures Physical Factors Sunspot activity sends more insolation to the earth Dust from volcanoes reflects away insolation Changes In Global Temperatures Physical Factors If the earth’s orbit changes we can be further from the sun and start to cool. Changes In Global Temperatures Physical Factors If the earth tilts away from the sun the Northern Hemisphere will cool Changes In Global Temperatures Human Factors CO2 absorbs heat and reradiates heating up the earth. Deforestation adds CO2 when trees burnt and less CO2 converted into water by trees. Methane, Nitrous Oxides & CFC emissions do the same as CO2. Inter Tropical Convergence Zone (ITCZ) This is simply the area between the two Tropics (Cancer & Capricorn) where two different air masses meet. As it is a low pressure area/belt there is rain. This is a result of the high levels of insolation at the equator causing the movement of warm air upwards. First try and work out a few definitions for Task 16, use your knowledge of the English language & your teacher to help. Inter Tropical Convergence Zone (ITCZ) Inter Tropical Convergence Zone between the tropics of Cancer & Capricorn. where two or more things meets in this case air masses an area Task 16 ? ITCZ ITCZ • The migration of the inter-tropical convergence zone (ITCZ) in Africa affects seasonal rainfall patterns across the continent. • It is an area of low pressure that forms where the Trade Winds meet near the earth's equator. • As these winds converge, moist air is forced upward. As it rises, the air cools, resulting in a band of heavy rain around the globe. • This band moves seasonally, due to the changing position of the overhead sun. Position of the ITCZ: January Tropic of Cancer Equator Tropic of Capricorn Task 17 ITCZ Air Masses Tropical Continental (cT) Dry Air masses = ? Tropical climate = ? & why Maritime climate = ? & why Continental climate = ? & why When describing air masses you must say; Where they develop Where they move to How stable they are Tropical Maritime (mT) Wet Their temperature & moisture characteristics What the weather will be like Task 18 ITCZ January Tropical Continental Dry Rain as sun & ITCZ located over Tropic of Capricorn Dry area north of ITCZ as Continental air is dry and stable, from Sahara Desert ITCZ Tropical Maritime Wet Task 18 ITCZ March Tropical Continental Dry Rain around equator as ITCZ located by it Wet area south of ITCZ as Maritime air is wet and unstable Tropical Maritime Wet Dry area north of ITCZ as Continental air is dry and stable Task 18 ITCZ July Tropical Continental Dry Rain as sun and ITCZ located over Tropic of Cancer ITCZ Wet area just south of ITCZ as Maritime air is wet and unstable Tropical Maritime Wet Some convectional rainfall between 5º N & S of the equator. Task 18 ITCZ September Tropical Continental Dry Rain around equator as ITCZ located by it Wet area south of ITCZ as Maritime air is wet and unstable Tropical Maritime Wet Dry area north of ITCZ as Continental air is dry and stable January Tropic of Cancer I T C Z Equator Tropic of Capricorn March Tropic of Cancer I T C Z Equator Tropic of Capricorn July Tropic of Cancer I T C Z Equator Tropic of Capricorn September Tropic of Cancer I T C Z Equator Tropic of Capricorn January Tropic of Cancer I T C Z Equator Tropic of Capricorn March Tropic of Cancer I T C Z Equator Tropic of Capricorn July Tropic of Cancer I T C Z Equator Tropic of Capricorn September Tropic of Cancer I T C Z Equator Tropic of Capricorn January Tropic of Cancer I T C Z Equator Tropic of Capricorn