Presentation on theme: "Weather and Climate Please ensure that you have the glossary sheet each lesson and that you add to it when necessary. Learning objectives: Major Climatic."— Presentation transcript:
1Weather and ClimatePlease ensure that you have the glossary sheet each lesson and that you add to it when necessary.Learning objectives:Major Climatic ControlsKnow the structure of the atmosphere and its heat budgetUnderstand atmospheric circulation and surface windsKnow how latitude, altitude and ocean circulation affect climate.
2Know the structure of the atmosphere and its heat budget There are four vertical layers within the atmosphere, each with its own particular characteristics. The outer limit of the atmosphere is set at 1000km, but the vast majority of our weather and climate is found within the lower 12km.
3Beginning at the earth's surface, the four layers of the atmosphere are listed below: Troposphere - layer characteristics:Decrease of temperature with height (6.4 degrees per 1000m).Increase in wind speeds with height.Fall in pressure with height.An unstable layer due to the presence of cloud, pollution water vapour and dust.The tropopause marks the outer edge of the troposphere and the limit to the earth's weather and climate.Stratosphere - layer characteristics:Temperatures increase with height in this layer, and it is here that ozone is concentrated, which absorbs UV radiation from the sun.Winds increase with height but pressure falls.The boundary is marked by the stratopause.Mesosphere - layer characteristics:A rapid fall in temperature with height, caused by a lack of water vapour, cloud and dust).Temperatures are extremely low and winds high.Its boundary is marked by the mesopause.Thermosphere - layer characteristics:The outer layer of the atmosphere.A rapid increase in temperature with height, exceeding 1000 degrees.
4See my lovely diagram! Radiation All energy for the heating of the atmosphere comes from the sun, some energy is lost. Radiation varied with the orbit of the sun. Heating of the atmosphere takes place when the light energy from the sun reaches the ground.Short waveEnergy that comes from the sun and passes through the atmosphere to earth is in the form of short wave radiation or insolation. It is responsible for the Earth's weather and climate and is converted via photosynthesis to support all forms of life. It is easy to enter the atmosphere.Long waveOnce insolation has reached the surface of the Earth, it is converted into heat energy. The ground begins to warm and slowly heats the atmosphere above it, meaning that the atmosphere is warmed from ground level upwards. The amount of heating of the atmosphere that occurs depends on the surface (for example, water, ice, grass, sand) that is being heated. It is difficult for it to leave the Earth’s atmosphere.Albedoand InsolationIn the Geography A-Z look up the meanings of these terms and write them in your own words.See my lovely diagram!
6Review Name 4 ways short wave radiation is absorbed. Long wave radiation is....If incoming radiation was 84% at point X and 30% is reflected, what is albedo?What is the cycle for radiation to and from the Earths surface?
7Global energy Solar energy affects: The incoming solar radiation is short-wave. As the Earth heats up it radiates it’s own heat in the form of long-waves (infra-red). The albedo is the percentage of radiation that is reflected. This depends on the type of surface (e.g. sea, forest, ice, cloud thickness).TemperatureClimateAtmospheric motionPrecipitationOcean currentsWhat controls the amount of incoming solar radiation?The effect of latitudeIncoming radiation is more diffused at higher latitudes because of angle of curvatureXYX > Ysunspot activityelliptical earth’s orbitlatitudeday and night
8Exam Style Question Explain why the poles are cooler than the equator. 8 marksLevel 1 – simple statements/ description. No development/ linked thinking. 1-3 marksLevel 2 – some detail and depth of processes. Development and linked thinking. 4-8 marks
9Global energy Radiation balance at Earth’s surface positive balance 1251005025positive balanceAverage net radiation (w/m²)806040202040608025degrees from equator50100negative balance125How is the positive heat balance (net gain in heat radiation from the Sun) within the Tropics transferred?1. HorizontallyAir movements, including winds, cyclones, depressions and ocean currents.2. VerticallyConduction, convection and radiation.
10Global energy Explain why the surface temperature varies. Map source; noaaExplain why the surface temperature varies.
11How is heat transferred? Horizontal heat transfer:About 80% of heat transferred away from the tropics is carried by winds e.g. Jet stream, hurricanes, depressions. The rest is transferred by the movement of warm ocean currents.Vertical Heat transfer:Transferred vertically by radiation, conduction and convection. Latent heat also helps.Precipitation releases energy and warms up the atmosphere. Vertical movement can transfer heat from a positive budget and its linked to horizontal transfer.
12What factors affect insolation and heating of the atmosphere? Page 43 A2 AQAMake your own notes.Altitude of the sunAltitude of the landPrevailing windsLong-term effectsProportion of sea and landWhat factors affect insolation and heating of the atmosphere?Diurnal rangeOcean CurrentsLocal effectsOcean Conveyor beltUrbanisationAspectCloud coverAnnotate a world map to show areas where these factors play a part in temperature.Wild weather DVD
14Wind speed and direction Understand atmospheric circulation and surface windsWind speed and directionRossby wave propagationWind speed is affected by a number of factors that operate on a variety of scales (micro to macro) e.g. the pressure gradient, Rossby waves and jet streams and local weather conditions such as sea breezes and urban winds.Pressure gradient = difference in air pressure (millibars) between two points in the atmosphere or on the Earth’s surface.The > the P difference the faster the wind. Air flows from areas of HP to LPPressure gradient, Coriolis force and friction all combine to influence wind direction.Local weather conditions can also influence wind speed as the formation of tropical storms and hurricanes can drastically affect the velocity of the wind.
15Atmospheric circulation As air moves from HP to LP in the N. hemisphere, it is deflected to the right by the Coriolis force. In the S. hemisphere, air moving from HP to LP is deflected to the left by the Coriolis force.due to the Earth’s rotationUKEquatorLow pressureHigh pressurelowhigh60All points on the Earth’s surface have the same rotational velocity (they go round once per day)An object travelling away from the equator (e.g. wind) will eventually be heading east faster than the ground below it and will seem to be moved east by some mysterious "force". This movement is eastwards in the northern hemisphere and westwards in the southern hemisphere.The diagram illustrates how it affects winds in both hemispheres and shows why the prevailing UK winds are from the SW. Pressure also helps determine direction.
16Atmospheric circulation – Tri-cellular model Warm air from the tropics meets cold air from the pole at the POLAR FRONT causing depressionsAir gets deflected northwardsHeat from the Sun most intense at the EquatorAir cools and sinksHadleycellCold air sinksHeavy convection rainfallWarm air risesFerrelcellPolarcellWarm air rises and becomes unstableDry and stableDry and stableITCZEasterlies (winds)South-westerlies (winds)North-east trade windsNorth Pole60o30oEquatorHigh pressureDivergence zoneLow pressureConvergence zoneHigh pressureDivergence zoneLow pressureConvergence zone
17Atmospheric circulation – Rossby waves Bands of strong winds blowing around the globe in the upper atmosphere (about 10km to 15km above the surface). They drive surface weather systems like depressions. A slight change in their path is what caused the very wet summer in 2007.They are produced largely because the atmosphere in motion encounters barriers to its progress, and is forced to ascend (by the changing surface level), then descends under gravity.High pressure ridgeLow pressure troughCold airWarm airThe resultant compression and release of the air columns involved leads to alterations to the rates of "spin" of the air flow (vorticity – add to your glossary).Appalachian mountainsIn N.America, what triggers the Rossby waves?The Rocky Mountains, and to a much more limited extent, the Appalachians.
18Atmospheric circulation-Jet streams Jet streams are bands of even faster winds (300km/hr) within the Rossby waves at about 10km above the surface. Their position and strength relate to the surface temperature contrast between warm and cold areas on EarthCommercial airlines often make use of them to reduce fuel consumption.There are two jet streams:The Subtropical Jet (between Ferrel and Hadley cells) which exists as a mechanism to transport moisture and energy from the tropics polewards.The Polar Jet above the Polar Front (the boundary between polar and mid-latitude cells)Jet stream clouds south of Cape Blanc, north Atlantic coast of Africa Courtesy NASA
19Global energy - Major ocean currents Know how latitude, altitude and ocean circulation affect climate.Global energy - Major ocean currentsAtmospheric processes are closely linked to the oceans because they store massive amounts of heat energy (and water) which has a major influence on weather and climate. They are involved in the horizontal transfer of heat with warm currents carrying water towards the poles and cold currents towards the Equator. This has the effect of raising or cooling the surrounding sea and air temperature which affects coastal climate.Warm currentCold current