Presentation on theme: "Near-Earth Space: The Van Allen Belts. Nature of the Belts Discovered early in the space age with a Geiger counter. Energetic charged particles are trapped."— Presentation transcript:
Near-Earth Space: The Van Allen Belts
Nature of the Belts Discovered early in the space age with a Geiger counter. Energetic charged particles are trapped in the Earth’s magnetic field. The inner belt contains protons, and the outer contains electrons. The inner belt begins at only 100 km or so above ground.
Aurora Borealis from Yellowknife in Canada
Aurorae Solar wind particles are generally repelled by the magnetosphere, but some “sneak” into the atmosphere by running along magnetic field lines toward the poles. (Outer belt) Earth atmospheric particles sneak into the belts as well. (Inner belt) At ~100km altitude, solar wind particles collide with atmosphere particles to produce an auroral light display.
Comparison of Planetary Magnetic Fields Equatorial Field (Gauss) Mercury0.002 Venus< Earth0.305 Mars(0.0004) Jupiter4.2 Saturn0.20 Uranus0.23 Neptune
The space around the Earth is not exactly crowded, but there is a great deal of “space debris” in orbit around Earth.
Cosmic Rays: The penetration of energetic particles from space into the Earth’s atmosphere
The Earth at Night (light pollution)
Understanding Sky Color
Sky Color from Two Places
Structure of the Earth’s Atmosphere
The Ozone Layer Component
Antarctic Ozone Hole
Ozone Layer Ozone molecule = O 3 O 3 protects use from harmful solar UV radiation An efficient O 3 destruction mechanism involves chlorofluorocarbons (CFC’s – Cl, F, C): … A single Cl atom can be used 1000’s of times to break up ozone molecules! Catalyst
Ozone Trends North Pole South Pole
Energy Budget of the Earth
Global Warming: Trends and Effects The topic of global warming is complicated. The question is not whether warming exists, but its origin. Increased greenhouse gases (carbon dioxide, methane, etc) act like a blanket to block the escape of infrared “heat” light. The Earth has also undergone cycles in the past. The main concern is the impact and control of warming.
Share Question The Earth's surface absorbs energy from sunlight and then radiates about as much energy back into space. The best proof you can offer for this fact is that the average surface temperature on Earth is a) warming slowly. b) not warming rapidly. c) half light and half dark. d) warmer at the core than on the surface.
Weather Primarily driven by solar radiation. Other significant influences include: 1. Land mass and oceans 2. Planet rotation 3. Atmospheric composition oOzone oGreenhouse effect 4. Volcanic activity
The Hadley Cell: Fundamental circulation pattern because of the fact that planets are round.
Volcanoes and Resurfacing Magma is less dense than rock, and so rises from the interior This breaks through, giving a volcano Products –New rocks (esp. basalts) –Ash ( ~1mm ) –Cinders (~ 1cm ) The key point is that volcanoes lead to resurfacing and are evidence of an active planetary interior
Mount St. Helens
Rock Types Igneous (“ignus”=fire) - form from crystallization of molten rock –Magma - molten inside earth –Lava - molten on surface *Of planetary interest: –Basalt - fast cooling –Granite - slow cooling Sedimentary - formed by deposition of small particles which become cemented (e.g., sandstone, shales) Metamorphic - changed by heat, pressure, and/or chemistry (e.g., marble)
Crustal Plates and Tectonic Activity Earth’s surface (or crust) is not a single solid piece, but consists of large and small “plates” These plates slowly drift around At points of convergence, get volcanoes, mountain ranges, and earthquakes
Long Term Plate Drifting
Volcanic Activity on Earth and Relation to Motion of Plates
Recycling process and resurfacing effects
Interior Structure of the Earth
Detail of Earth Interior
Seismology Study of the Earth’s interior from how it carries vibrations Types of vibrations –P-waves: pressure waves that travel like sound –S-waves: shear waves, like on a rope Terminology: –Focus: point at which the earthquake originates –Epicenter: surface point above the focus –Seismometer: a device to measure P & S waves and the strength of earthquakes
Refraction of traveling sound waves in the Earth reveals its components
Shuddering of the Earth
Share Question Earthquakes are an important tool for scientists because their vibrations a) influence the Earth's orbit about the Sun b) allow the study of the Earth's internal structure c) inform us of the mass of the Earth d) are used to predict the future of plate tectonics
Earth’s Magnetic Field Lines of force are somewhat like a bar magnet. Its origin and maintenance comes from dynamo activity in the core: Circulation of conducting fluid (e.g., molten metals) generates magnetic fields. So, planetary magnetic fields act like probes of unseen planetary interiors
Share Question The Earth's magnetic dynamo is caused by a combination of convection in its molten core and a) the Earth's orbit around the Sun b) the Earth's rotation c) lunar tidal action d) the aurora borealis