Presentation on theme: "The Dynamic Earth External Radiant Energy From the Sun Drives Atmospheric and Hydrospheric Processes."— Presentation transcript:
1The Dynamic EarthExternal Radiant Energy From the Sun Drives Atmospheric and Hydrospheric Processes
2QuestionsHow does the greenhouse effect increase surface temperature of the Earth? What would happen to the temperature of the Earth if the concentration of greenhouse gases would increase or decrease?What does the Earth’s magnetic field protect us from? Does the Earth’s magnetic field extend beyond the atmosphere?What would happen to our atmosphere without the magnetic field?What is ozone and where is the ozone layer found?From what does the ozone layer protect us and how does this layer protect us?How does the Earth’s atmosphere and hydrosphere respond to differences in temperature on the Earth?What produces winds?What is the Coriolis Effect and which three wind belts do they produce?
3What does dynamic mean?Ever changing in varying degrees of intensity.
4What is the source of the Earth’s dynamic nature? A constant flow of external and internal energy.External Sources of EnergySunlight (Electromagnetic Radiation)Internal Sources of Energy (earth was hot when it started)Energy from Earth’s formationExtraterrestrial impactsGravitational contraction/compressionDecay of radioactive elements (Uranium, for example) This supplies internal energy to the earth to mostly compensate for any transfers into space.
5The Mechanism for Plate Motion is Convection in the Mantle Figure 1.12: Earth’s plates are thought to move as a result of underlying mantle convection cells in which warm material from deep within Earth rises toward the surface, cools, and then, on losing heat, descends back into the interior. The movement of these convection cells is thought to be the mechanism responsible for the movement of Earth’s plates, as shown in this diagrammatic cross section.The Mechanism for Plate Motion is Convection in the MantleFig. 1-12, p. 15
6Four Layers of the Earth’s Atmosphere Thermosphere (oxygen absorbs solar radiation and greatly increases the temperature)Mesosphere (cools with altitude)Stratosphere (contains the ozone layer, warms with altitude due to ozone layer absorbing UV rays)Troposphere (weather layer, cools with altitude)Base-ground level
9Atmospheric Layers Four Layers Thermosphere (outermost layer, receives intense solar radiation)Mesosphere (coldest layer)Stratosphere (contains the ozone layer, warmer due to absorption of ultra-violet light)Troposphere (the weather layer, the densest layer)Also, the Ionosphere (forms due to the interaction of cosmic radiation from the Sun with the faint nitrogen and oxygen concentration in the thermosphere)
10Earth’s Atmospheric Composition Table 1: Average composition of the atmosphere up to an altitude of 25 km.Gas NameChemical FormulaPercent VolumeNitrogenN278.08%OxygenO220.95%*Water^H2O0 to 4%ArgonAr0.93%*Carbon dioxide^CO20.0360%NeonNe0.0018%HeliumHe0.0005%*Methane^CH4%HydrogenH2%*Nitrous oxide^N2O%*OzoneO3%* variable gases ^ greenhouse gasesAll of these make up less than 1% of the Earth’s atmosphere!!Source:
11Atmospheric Evolution Primordial atmosphere contained mostly carbon dioxide and nitrogen, with some ammonia and hydrogen—volcanic gases.2.5 billion years ago, a change occurred, plant cells algae, began to consume carbon dioxide and give off oxygen (photosynthesis)Atmosphere gradually filled with oxygen350 million years ago…basically same level of oxygen as today.
12Earth’s Protection System Ozone Layer (UV ray absorber/shield)Greenhouse Effect (Thermal insulating blanket produced by greenhouse gases)Earth’s Magnetic Field (Solar wind blocker and atmospheric erosion protector)
13Without the Ozone Layer No terrestrial life (UV rays are dangerous to life: DNA destroyed for example)
14Ozone LayerOzone absorbs the majority of incoming ultra-violet light from the Sun.Ozone is composed of three oxygen atoms, and is toxic to humans.Ozone holes or thinning is primarily caused by CFCs (chlorofluorocarbons)—used in aerosol sprays, now banned worldwide.Some evidence of the “healing” of the ozone layer is observed, however, it is estimated that it should recover in another 2-3 decades without CFCs.
15Without the Magnetic Field Atmosphere would be eroded by the solar wind, and cosmic radiation (high-speed high energy electrons and protons from the Sun) would harm living organisms and strip away the ozone layer.
17The Earth’s Magnetic Field Protects us from the Solar Wind Solar wind consists of charged particles moving away from the Sun.
18Ingredients for the Aurora Planet must have a magnetic fieldPlanet must receive charged particles from Sun in the solar wind (protons, electrons, alpha particles)Planet must have an atmosphere
19Near the magnetic poles, these particles sometimes leak into our atmosphere, causing the gases to glow. This is known as the aurora.
20Production of an Aurora Some high-speed charged particles from the Sun’s solar wind are drawn towards the poles by the Earth’s magnetic field lines.The particles interact with gas particles in the atmosphere, causing them to glow.
21Without the Greenhouse Gases Earth would much colder and iced over (-27 degrees C avg. surface temperature, compared to degrees C with greenhouse gases)
22Greenhouse EffectThe surface of the Earth absorbs mostly shorter wavelength visible light from the Sun. Due to the increase in temperature, the Earth then reradiates energy as infrared light.The presence of greenhouse gases, CO2 and H2O and methane (CH4) and a few other trace gases, serve to absorb some of the infrared light radiated from the Earth’s surface.Visible light’s wavelength is too short to be absorbed by these greenhouse gases on the way in, but infrared light’s wavelength is longer and can be absorbed.This leads to increased surface temperature.
2313. How does the greenhouse effect help keep the Earth’s surface warm?
24The greenhouse effect is the warming of a planet’s surface due to the trapping of terrestrial long-wave infrared radiation by the greenhouse gases in the planet’s atmosphere.
26Radiant Heat and Atmospheric- Heat Flow Which part of the Earth receives the most energy from the Sun?The equator!How does this influence the flow of heat on Earth?Since heat flows from hot to cold, the heat flows away from the equator towards the poles.
27Earth’s Thermal Energy Cycle Excess heat (thermal energy) accumulates in the vicinity of the Earth’s equator.This heats the atmosphere and the Earth’s oceans.Heat or thermal energy is moved away from the equator to the poles to equalize the temperature of the Earth—Earth strikes a balance.
28Earth’s Thermal Energy Cycle How does the Earth correct for this imbalance in thermal energy (hot equator, cold poles)?Winds form a convection current from the equator to poles (warm air moves to the poles, is cooled and returns to be heated).Ocean currents carry warm water to the poles and, when cooled, the cooler water from the poles circulates to the equator to be heated again.
29Atmosphere Pressure and Wind What causes the wind?Differences in atmospheric pressure.What causes differences in atmospheric pressure?Differences in the heating of the Earth’s surface.What causes differences in the heating of the Earth’s surface?Three reasonsAngle of the sunlight striking the Earth’s surfaceDuration of the sunlightRatio of sunlight being reflected vs. absorbed
30Wind Belts and the Coriolis Effect Without the rotation of the Earth, two main convection cells would operate, from equator to poles.With the rotation, the winds are deflected either east or west, due to the Coriolis effect.Winds from the poles are deflected to the west, winds from the equator are deflected to the east.These are the prevailing winds (trade winds, westerlies and polar easterlies)
31Two Atmospheric Convection Cells Heat flow by Convection—Warmer atmosphere rises and moves towards the poles, sinks at the poles and moves back toward the equatorWith no rotation of Earth
32Coriolis Effect breaks up the two hemispheric convection cells into 6 distinct global wind belts
33Coriolis EffectThe apparent change in the direction of an object’s path due to the Earth’s rotation.
34Coriolis Effect-Apparent motion of objects in northern hemisphere as observed from their origin is to the right.-Apparent motion of objects in the southern hemisphere as observed from their origin is to the left.
35Coriolis Effect-Winds that move toward the poles move east (Earth is spinning slower relative to the speed of the wind—wind moves ahead)-Winds that move toward the equator move west (Earth is spinning faster relative to the speed of the wind—wind falls behind.
361) Polar easterlies 2) Prevailing westerlies 3) Tropical easterlies Global Wind BeltsThe two atmospheric convection cells that move from the equator to the poles are modified by the Coriolis Effect because the Earth rotates. This forms the global wind belts.
37Coriolis Effect and Winds -Winds in the northern hemisphere curve clockwise-Winds in the southern hemisphere curve counterclockwise.
38Rising air leads to low pressure near the surface and sinking air leads to high pressure near the surface. This leads to semi-permanent pressure zones on the earth because of these three circulation cells. See figure 2. Figure 2 In addition, as air travels along, it experiences the coriolis force because of earth's rotation. This force tends to deflect motion the the right in the northern hemisphere and to the left in the southern hemisphere. The combination of the three (six) major circulation cells, the semi-permanent pressure zones and the coriolis force cause the generalized circulation patterns seen in the figures. (i.e. "Easterlies" and "Westerlies")
39Ocean Currents Surface ocean currents circulate throughout the Earth. Surface ocean currents are produced by the prevailing wind belts blowing over the water’s surface.Warm water currents transfer heat towards the poles
40Gulf Stream brings warm water northeast from the Caribbean. 21.7 The High Specific Heat Capacity of WaterWater’s capacity to store heat affects the global climate.Water stores and hold heat well because of its high specific heat.Gulf Stream brings warm water northeast from the Caribbean.