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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. - PowerPoint PPT Presentation
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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.
Aurorae
Space Aurora
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)
Mercury 0.002Venus <0.0003Earth 0.305Mars (0.0004)
Jupiter 4.2Saturn 0.20Uranus 0.23
Neptune 0.06-1.2
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)
Sky Appearance
Understanding Sky Color
Sky Color from Two Places
Structure of the Earth’s Atmosphere
The Ozone Layer Component
Antarctic Ozone Hole
Ozone LayerOzone molecule = O3
O3 protects use from harmful solar UV radiationAn efficient O3 destruction mechanism involves
chlorofluorocarbons (CFC’s – Cl, F, C):
<chemistry> …
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.
Climate Regulation
Share QuestionThe 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 oceans2. Planet rotation3. Atmospheric composition
o Ozoneo Greenhouse effect
4. Volcanic activity
The Hadley Cell: Fundamental circulation pattern because of the fact that planets are
round.
Coriolis Deflection: Planet rotation causes north-south weather circulation to deflect
east-west.
The Coriolis Force
Hadley Cells on the Earth
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
Tungurahua (Andes)
Rock TypesIgneous (“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
Crustal Plates
Long Term Plate Drifting
Plate Motion
Volcanic Activity on Earth and Relation to
Motion of Plates
Recycling process and resurfacing effects
Interior Structure of the Earth
Detail of Earth Interior
SeismologyStudy 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
Earthquake
Wave Forms
Refraction of traveling sound waves in the Earth reveals its
components
Shuddering of the Earth
Share QuestionEarthquakes 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
Earth Dynamo
Share QuestionThe 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